9 .Nd User interface for firewall, traffic shaper, packet scheduler,
12 .Ss FIREWALL CONFIGURATION
21 .Op Ar rule | first-last ...
29 .Brq Cm delete | zero | resetlog
33 .Cm set Oo Cm disable Ar number ... Oc Op Cm enable Ar number ...
37 .Ar number Cm to Ar number
39 .Cm set swap Ar number number
45 .Brq Cm firewall | altq | one_pass | debug | verbose | dyn_keepalive
48 .Brq Cm firewall | altq | one_pass | debug | verbose | dyn_keepalive
51 .Oo Cm set Ar N Oc Cm table Ar name Cm create Ar create-options
53 .Oo Cm set Ar N Oc Cm table
57 .Oo Cm set Ar N Oc Cm table Ar name Cm modify Ar modify-options
59 .Oo Cm set Ar N Oc Cm table Ar name Cm swap Ar name
61 .Oo Cm set Ar N Oc Cm table Ar name Cm add Ar table-key Op Ar value
63 .Oo Cm set Ar N Oc Cm table Ar name Cm add Op Ar table-key Ar value ...
65 .Oo Cm set Ar N Oc Cm table Ar name Cm atomic add Op Ar table-key Ar value ...
67 .Oo Cm set Ar N Oc Cm table Ar name Cm delete Op Ar table-key ...
69 .Oo Cm set Ar N Oc Cm table Ar name Cm lookup Ar addr
71 .Oo Cm set Ar N Oc Cm table Ar name Cm lock
73 .Oo Cm set Ar N Oc Cm table Ar name Cm unlock
75 .Oo Cm set Ar N Oc Cm table
79 .Oo Cm set Ar N Oc Cm table
83 .Oo Cm set Ar N Oc Cm table
87 .Oo Cm set Ar N Oc Cm table
90 .Ss DUMMYNET CONFIGURATION (TRAFFIC SHAPER AND PACKET SCHEDULER)
92 .Brq Cm pipe | queue | sched
98 .Brq Cm pipe | queue | sched
99 .Brq Cm delete | list | show
113 .Ss STATEFUL IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
115 .Oo Cm set Ar N Oc Cm nat64lsn Ar name Cm create Ar create-options
117 .Oo Cm set Ar N Oc Cm nat64lsn Ar name Cm config Ar config-options
119 .Oo Cm set Ar N Oc Cm nat64lsn
124 .Oo Cm set Ar N Oc Cm nat64lsn
128 .Oo Cm set Ar N Oc Cm nat64lsn Ar name Cm stats Op Cm reset
129 .Ss STATELESS IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
131 .Oo Cm set Ar N Oc Cm nat64stl Ar name Cm create Ar create-options
133 .Oo Cm set Ar N Oc Cm nat64stl Ar name Cm config Ar config-options
135 .Oo Cm set Ar N Oc Cm nat64stl
139 .Oo Cm set Ar N Oc Cm nat64stl
143 .Oo Cm set Ar N Oc Cm nat64stl Ar name Cm stats Op Cm reset
144 .Ss XLAT464 CLAT IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
146 .Oo Cm set Ar N Oc Cm nat64clat Ar name Cm create Ar create-options
148 .Oo Cm set Ar N Oc Cm nat64clat Ar name Cm config Ar config-options
150 .Oo Cm set Ar N Oc Cm nat64clat
154 .Oo Cm set Ar N Oc Cm nat64clat
158 .Oo Cm set Ar N Oc Cm nat64clat Ar name Cm stats Op Cm reset
159 .Ss IPv6-to-IPv6 NETWORK PREFIX TRANSLATION
161 .Oo Cm set Ar N Oc Cm nptv6 Ar name Cm create Ar create-options
163 .Oo Cm set Ar N Oc Cm nptv6
167 .Oo Cm set Ar N Oc Cm nptv6
171 .Oo Cm set Ar N Oc Cm nptv6 Ar name Cm stats Op Cm reset
172 .Ss INTERNAL DIAGNOSTICS
179 .Ss LIST OF RULES AND PREPROCESSING
192 utility is the user interface for controlling the
196 traffic shaper/packet scheduler, and the
197 in-kernel NAT services.
199 A firewall configuration, or
203 numbered from 1 to 65535.
204 Packets are passed to the firewall
205 from a number of different places in the protocol stack
206 (depending on the source and destination of the packet,
207 it is possible for the firewall to be
208 invoked multiple times on the same packet).
209 The packet passed to the firewall is compared
210 against each of the rules in the
213 (multiple rules with the same number are permitted, in which case
214 they are processed in order of insertion).
215 When a match is found, the action corresponding to the
216 matching rule is performed.
218 Depending on the action and certain system settings, packets
219 can be reinjected into the firewall at some rule after the
220 matching one for further processing.
222 A ruleset always includes a
224 rule (numbered 65535) which cannot be modified or deleted,
225 and matches all packets.
226 The action associated with the
232 depending on how the kernel is configured.
234 If the ruleset includes one or more rules with the
241 the firewall will have a
243 behaviour, i.e., upon a match it will create
245 i.e., rules that match packets with the same 5-tuple
246 (protocol, source and destination addresses and ports)
247 as the packet which caused their creation.
248 Dynamic rules, which have a limited lifetime, are checked
249 at the first occurrence of a
254 rule, and are typically used to open the firewall on-demand to
255 legitimate traffic only.
262 for all packets (not only these matched by the rule) but
269 .Sx STATEFUL FIREWALL
272 Sections below for more information on the stateful behaviour of
275 All rules (including dynamic ones) have a few associated counters:
276 a packet count, a byte count, a log count and a timestamp
277 indicating the time of the last match.
278 Counters can be displayed or reset with
282 Each rule belongs to one of 32 different
286 commands to atomically manipulate sets, such as enable,
287 disable, swap sets, move all rules in a set to another
288 one, delete all rules in a set.
289 These can be useful to
290 install temporary configurations, or to test them.
293 for more information on
296 Rules can be added with the
298 command; deleted individually or in groups with the
300 command, and globally (except those in set 31) with the
302 command; displayed, optionally with the content of the
308 Finally, counters can be reset with the
314 The following general options are available when invoking
316 .Bl -tag -width indent
318 Show counter values when listing rules.
321 command implies this option.
323 Only show the action and the comment, not the body of a rule.
327 When entering or showing rules, print them in compact form,
328 i.e., omitting the "ip from any to any" string
329 when this does not carry any additional information.
331 When listing, show dynamic rules in addition to static ones.
333 When listing, show only dynamic states.
334 When deleting, delete only dynamic states.
336 Run without prompting for confirmation for commands that can cause problems if misused,
339 If there is no tty associated with the process, this is implied.
342 command with this flag ignores possible errors,
343 i.e., nonexistent rule number.
344 And for batched commands execution continues with the next command.
346 When listing a table (see the
348 section below for more information on lookup tables), format values
350 By default, values are shown as integers.
352 Only check syntax of the command strings, without actually passing
355 Try to resolve addresses and service names in output.
357 Be quiet when executing the
367 This is useful when updating rulesets by executing multiple
371 .Ql sh\ /etc/rc.firewall ) ,
372 or by processing a file with many
374 rules across a remote login session.
375 It also stops a table add or delete
376 from failing if the entry already exists or is not present.
378 The reason why this option may be important is that
379 for some of these actions,
381 may print a message; if the action results in blocking the
382 traffic to the remote client,
383 the remote login session will be closed
384 and the rest of the ruleset will not be processed.
385 Access to the console would then be required to recover.
387 When listing rules, show the
389 each rule belongs to.
390 If this flag is not specified, disabled rules will not be
393 When listing pipes, sort according to one of the four
394 counters (total or current packets or bytes).
396 When listing, show last match timestamp converted with
399 When listing, show last match timestamp as seconds from the epoch.
400 This form can be more convenient for postprocessing by scripts.
402 .Ss LIST OF RULES AND PREPROCESSING
403 To ease configuration, rules can be put into a file which is
406 as shown in the last synopsis line.
410 The file will be read line by line and applied as arguments to the
414 Optionally, a preprocessor can be specified using
418 is to be piped through.
419 Useful preprocessors include
425 does not start with a slash
427 as its first character, the usual
429 name search is performed.
430 Care should be taken with this in environments where not all
431 file systems are mounted (yet) by the time
433 is being run (e.g.\& when they are mounted over NFS).
436 has been specified, any additional arguments are passed on to the preprocessor
438 This allows for flexible configuration files (like conditionalizing
439 them on the local hostname) and the use of macros to centralize
440 frequently required arguments like IP addresses.
441 .Ss TRAFFIC SHAPER CONFIGURATION
447 commands are used to configure the traffic shaper and packet scheduler.
449 .Sx TRAFFIC SHAPER (DUMMYNET) CONFIGURATION
450 Section below for details.
452 If the world and the kernel get out of sync the
454 ABI may break, preventing you from being able to add any rules.
455 This can adversely affect the booting process.
460 to temporarily disable the firewall to regain access to the network,
461 allowing you to fix the problem.
463 A packet is checked against the active ruleset in multiple places
464 in the protocol stack, under control of several sysctl variables.
465 These places and variables are shown below, and it is important to
466 have this picture in mind in order to design a correct ruleset.
467 .Bd -literal -offset indent
470 +----------->-----------+
472 [ip(6)_input] [ip(6)_output] net.inet(6).ip(6).fw.enable=1
475 [ether_demux] [ether_output_frame] net.link.ether.ipfw=1
477 +-->--[bdg_forward]-->--+ net.link.bridge.ipfw=1
483 times the same packet goes through the firewall can
484 vary between 0 and 4 depending on packet source and
485 destination, and system configuration.
487 Note that as packets flow through the stack, headers can be
488 stripped or added to it, and so they may or may not be available
490 E.g., incoming packets will include the MAC header when
494 but the same packets will have the MAC header stripped off when
501 Also note that each packet is always checked against the complete ruleset,
502 irrespective of the place where the check occurs, or the source of the packet.
503 If a rule contains some match patterns or actions which are not valid
504 for the place of invocation (e.g.\& trying to match a MAC header within
508 the match pattern will not match, but a
510 operator in front of such patterns
514 match on those packets.
515 It is thus the responsibility of
516 the programmer, if necessary, to write a suitable ruleset to
517 differentiate among the possible places.
519 rules can be useful here, as an example:
520 .Bd -literal -offset indent
521 # packets from ether_demux or bdg_forward
522 ipfw add 10 skipto 1000 all from any to any layer2 in
523 # packets from ip_input
524 ipfw add 10 skipto 2000 all from any to any not layer2 in
525 # packets from ip_output
526 ipfw add 10 skipto 3000 all from any to any not layer2 out
527 # packets from ether_output_frame
528 ipfw add 10 skipto 4000 all from any to any layer2 out
531 (yes, at the moment there is no way to differentiate between
532 ether_demux and bdg_forward).
534 Also note that only actions
543 frames and all other actions act as if they were
546 Full set of actions is supported for IP packets without
551 action does not divert
555 In general, each keyword or argument must be provided as
556 a separate command line argument, with no leading or trailing
558 Keywords are case-sensitive, whereas arguments may
559 or may not be case-sensitive depending on their nature
560 (e.g.\& uid's are, hostnames are not).
562 Some arguments (e.g., port or address lists) are comma-separated
564 In this case, spaces after commas ',' are allowed to make
565 the line more readable.
566 You can also put the entire
567 command (including flags) into a single argument.
568 E.g., the following forms are equivalent:
569 .Bd -literal -offset indent
570 ipfw -q add deny src-ip 10.0.0.0/24,127.0.0.1/8
571 ipfw -q add deny src-ip 10.0.0.0/24, 127.0.0.1/8
572 ipfw "-q add deny src-ip 10.0.0.0/24, 127.0.0.1/8"
575 The format of firewall rules is the following:
576 .Bd -ragged -offset indent
579 .Op Cm set Ar set_number
580 .Op Cm prob Ar match_probability
582 .Op Cm log Op Cm logamount Ar number
592 where the body of the rule specifies which information is used
593 for filtering packets, among the following:
595 .Bl -tag -width "Source and dest. addresses and ports" -offset XXX -compact
596 .It Layer2 header fields
598 .It IPv4 and IPv6 Protocol
599 SCTP, TCP, UDP, ICMP, etc.
600 .It Source and dest. addresses and ports
604 .It Transmit and receive interface
606 .It Misc. IP header fields
607 Version, type of service, datagram length, identification,
611 .It IPv6 Extension headers
612 Fragmentation, Hop-by-Hop options,
613 Routing Headers, Source routing rthdr0, Mobile IPv6 rthdr2, IPSec options.
615 .It Misc. TCP header fields
616 TCP flags (SYN, FIN, ACK, RST, etc.),
617 sequence number, acknowledgment number,
625 When the packet can be associated with a local socket.
627 Whether a packet came from a divert socket (e.g.,
629 .It Fib annotation state
630 Whether a packet has been tagged for using a specific FIB (routing table)
631 in future forwarding decisions.
634 Note that some of the above information, e.g.\& source MAC or IP addresses and
635 TCP/UDP ports, can be easily spoofed, so filtering on those fields
636 alone might not guarantee the desired results.
637 .Bl -tag -width indent
639 Each rule is associated with a
641 in the range 1..65535, with the latter reserved for the
644 Rules are checked sequentially by rule number.
645 Multiple rules can have the same number, in which case they are
646 checked (and listed) according to the order in which they have
648 If a rule is entered without specifying a number, the kernel will
649 assign one in such a way that the rule becomes the last one
653 Automatic rule numbers are assigned by incrementing the last
654 non-default rule number by the value of the sysctl variable
655 .Ar net.inet.ip.fw.autoinc_step
656 which defaults to 100.
657 If this is not possible (e.g.\& because we would go beyond the
658 maximum allowed rule number), the number of the last
659 non-default value is used instead.
660 .It Cm set Ar set_number
661 Each rule is associated with a
664 Sets can be individually disabled and enabled, so this parameter
665 is of fundamental importance for atomic ruleset manipulation.
666 It can be also used to simplify deletion of groups of rules.
667 If a rule is entered without specifying a set number,
670 Set 31 is special in that it cannot be disabled,
671 and rules in set 31 are not deleted by the
673 command (but you can delete them with the
674 .Nm ipfw delete set 31
676 Set 31 is also used for the
679 .It Cm prob Ar match_probability
680 A match is only declared with the specified probability
681 (floating point number between 0 and 1).
682 This can be useful for a number of applications such as
683 random packet drop or
686 to simulate the effect of multiple paths leading to out-of-order
689 Note: this condition is checked before any other condition, including
696 .It Cm log Op Cm logamount Ar number
697 Packets matching a rule with the
699 keyword will be made available for logging in two ways:
700 if the sysctl variable
701 .Va net.inet.ip.fw.verbose
702 is set to 0 (default), one can use
707 This pseudo interface can be created manually after a system
708 boot by using the following command:
709 .Bd -literal -offset indent
710 # ifconfig ipfw0 create
713 Or, automatically at boot time by adding the following
717 .Bd -literal -offset indent
721 There is zero overhead when no
723 is attached to the pseudo interface.
726 .Va net.inet.ip.fw.verbose
727 is set to 1, packets will be logged to
731 facility up to a maximum of
736 is specified, the limit is taken from the sysctl variable
737 .Va net.inet.ip.fw.verbose_limit .
738 In both cases, a value of 0 means unlimited logging.
740 Once the limit is reached, logging can be re-enabled by
741 clearing the logging counter or the packet counter for that entry, see the
745 Note: logging is done after all other packet matching conditions
746 have been successfully verified, and before performing the final
747 action (accept, deny, etc.) on the packet.
749 When a packet matches a rule with the
751 keyword, the numeric tag for the given
753 in the range 1..65534 will be attached to the packet.
754 The tag acts as an internal marker (it is not sent out over
755 the wire) that can be used to identify these packets later on.
756 This can be used, for example, to provide trust between interfaces
757 and to start doing policy-based filtering.
758 A packet can have multiple tags at the same time.
759 Tags are "sticky", meaning once a tag is applied to a packet by a
760 matching rule it exists until explicit removal.
761 Tags are kept with the packet everywhere within the kernel, but are
762 lost when packet leaves the kernel, for example, on transmitting
763 packet out to the network or sending packet to a
767 To check for previously applied tags, use the
770 To delete previously applied tag, use the
774 Note: since tags are kept with the packet everywhere in kernelspace,
775 they can be set and unset anywhere in the kernel network subsystem
778 facility), not only by means of the
784 For example, there can be a specialized
786 node doing traffic analyzing and tagging for later inspecting
788 .It Cm untag Ar number
789 When a packet matches a rule with the
791 keyword, the tag with the number
793 is searched among the tags attached to this packet and,
794 if found, removed from it.
795 Other tags bound to packet, if present, are left untouched.
797 When a packet matches a rule with the
799 keyword, the ALTQ identifier for the given
804 Note that this ALTQ tag is only meaningful for packets going "out" of IPFW,
805 and not being rejected or going to divert sockets.
806 Note that if there is insufficient memory at the time the packet is
807 processed, it will not be tagged, so it is wise to make your ALTQ
808 "default" queue policy account for this.
811 rules match a single packet, only the first one adds the ALTQ classification
813 In doing so, traffic may be shaped by using
814 .Cm count Cm altq Ar queue
815 rules for classification early in the ruleset, then later applying
816 the filtering decision.
821 rules may come later and provide the actual filtering decisions in
822 addition to the fallback ALTQ tag.
826 to set up the queues before IPFW will be able to look them up by name,
827 and if the ALTQ disciplines are rearranged, the rules in containing the
828 queue identifiers in the kernel will likely have gone stale and need
830 Stale queue identifiers will probably result in misclassification.
832 All system ALTQ processing can be turned on or off via
837 .Cm disable Ar altq .
839 .Va net.inet.ip.fw.one_pass
840 is irrelevant to ALTQ traffic shaping, as the actual rule action is followed
841 always after adding an ALTQ tag.
844 A rule can be associated with one of the following actions, which
845 will be executed when the packet matches the body of the rule.
846 .Bl -tag -width indent
847 .It Cm allow | accept | pass | permit
848 Allow packets that match rule.
849 The search terminates.
850 .It Cm check-state Op Ar :flowname | Cm :any
851 Checks the packet against the dynamic ruleset.
852 If a match is found, execute the action associated with
853 the rule which generated this dynamic rule, otherwise
854 move to the next rule.
857 rules do not have a body.
860 rule is found, the dynamic ruleset is checked at the first
867 is symbolic name assigned to dynamic rule by
872 can be used to ignore states flowname when matching.
875 keyword is special name used for compatibility with old rulesets.
877 Update counters for all packets that match rule.
878 The search continues with the next rule.
880 Discard packets that match this rule.
881 The search terminates.
882 .It Cm divert Ar port
883 Divert packets that match this rule to the
887 The search terminates.
888 .It Cm fwd | forward Ar ipaddr | tablearg Ns Op , Ns Ar port
889 Change the next-hop on matching packets to
891 which can be an IP address or a host name.
892 The next hop can also be supplied by the last table
893 looked up for the packet by using the
895 keyword instead of an explicit address.
896 The search terminates if this rule matches.
900 is a local address, then matching packets will be forwarded to
902 (or the port number in the packet if one is not specified in the rule)
903 on the local machine.
907 is not a local address, then the port number
908 (if specified) is ignored, and the packet will be
909 forwarded to the remote address, using the route as found in
910 the local routing table for that IP.
914 rule will not match layer2 packets (those received
915 on ether_input, ether_output, or bridged).
919 action does not change the contents of the packet at all.
920 In particular, the destination address remains unmodified, so
921 packets forwarded to another system will usually be rejected by that system
922 unless there is a matching rule on that system to capture them.
923 For packets forwarded locally,
924 the local address of the socket will be
925 set to the original destination address of the packet.
928 entry look rather weird but is intended for
929 use with transparent proxy servers.
930 .It Cm nat Ar nat_nr | global | tablearg
933 (for network address translation, address redirect, etc.):
935 .Sx NETWORK ADDRESS TRANSLATION (NAT)
936 Section for further information.
937 .It Cm nat64lsn Ar name
938 Pass packet to a stateful NAT64 instance (for IPv6/IPv4 network address and
939 protocol translation): see the
940 .Sx IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
941 Section for further information.
942 .It Cm nat64stl Ar name
943 Pass packet to a stateless NAT64 instance (for IPv6/IPv4 network address and
944 protocol translation): see the
945 .Sx IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
946 Section for further information.
947 .It Cm nat64clat Ar name
948 Pass packet to a CLAT NAT64 instance (for client-side IPv6/IPv4 network address and
949 protocol translation): see the
950 .Sx IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
951 Section for further information.
953 Pass packet to a NPTv6 instance (for IPv6-to-IPv6 network prefix translation):
955 .Sx IPv6-to-IPv6 NETWORK PREFIX TRANSLATION (NPTv6)
956 Section for further information.
957 .It Cm pipe Ar pipe_nr
961 (for bandwidth limitation, delay, etc.).
963 .Sx TRAFFIC SHAPER (DUMMYNET) CONFIGURATION
964 Section for further information.
965 The search terminates; however, on exit from the pipe and if
969 .Va net.inet.ip.fw.one_pass
970 is not set, the packet is passed again to the firewall code
971 starting from the next rule.
972 .It Cm queue Ar queue_nr
976 (for bandwidth limitation using WF2Q+).
982 Discard packets that match this rule, and if the
983 packet is a TCP packet, try to send a TCP reset (RST) notice.
984 The search terminates.
986 Discard packets that match this rule, and if the
987 packet is a TCP packet, try to send a TCP reset (RST) notice.
988 The search terminates.
989 .It Cm skipto Ar number | tablearg
990 Skip all subsequent rules numbered less than
992 The search continues with the first rule numbered
995 It is possible to use the
997 keyword with a skipto for a
1000 Skipto may work either in O(log(N)) or in O(1) depending
1001 on amount of memory and/or sysctl variables.
1003 .Sx SYSCTL VARIABLES
1004 section for more details.
1005 .It Cm call Ar number | tablearg
1006 The current rule number is saved in the internal stack and
1007 ruleset processing continues with the first rule numbered
1010 If later a rule with the
1012 action is encountered, the processing returns to the first rule
1015 rule plus one or higher
1016 (the same behaviour as with packets returning from
1021 This could be used to make somewhat like an assembly language
1023 calls to rules with common checks for different interfaces, etc.
1025 Rule with any number could be called, not just forward jumps as with
1027 So, to prevent endless loops in case of mistakes, both
1031 actions don't do any jumps and simply go to the next rule if memory
1032 cannot be allocated or stack overflowed/underflowed.
1034 Internally stack for rule numbers is implemented using
1036 facility and currently has size of 16 entries.
1037 As mbuf tags are lost when packet leaves the kernel,
1039 should not be used in subroutines to avoid endless loops
1040 and other undesired effects.
1042 Takes rule number saved to internal stack by the last
1044 action and returns ruleset processing to the first rule
1045 with number greater than number of corresponding
1048 See description of the
1050 action for more details.
1056 and thus are unconditional, but
1058 command-line utility currently requires every action except
1061 While it is sometimes useful to return only on some packets,
1062 usually you want to print just
1065 A workaround for this is to use new syntax and
1068 .Bd -literal -offset indent
1069 # Add a rule without actual body
1070 ipfw add 2999 return via any
1072 # List rules without "from any to any" part
1076 This cosmetic annoyance may be fixed in future releases.
1078 Send a copy of packets matching this rule to the
1080 socket bound to port
1082 The search continues with the next rule.
1083 .It Cm unreach Ar code Op mtu
1084 Discard packets that match this rule, and try to send an ICMP
1085 unreachable notice with code
1089 is a number from 0 to 255, or one of these aliases:
1090 .Cm net , host , protocol , port ,
1091 .Cm needfrag , srcfail , net-unknown , host-unknown ,
1092 .Cm isolated , net-prohib , host-prohib , tosnet ,
1093 .Cm toshost , filter-prohib , host-precedence
1095 .Cm precedence-cutoff .
1098 code may have an optional
1101 If specified, the MTU value will be put into generated ICMP packet.
1102 The search terminates.
1103 .It Cm unreach6 Ar code
1104 Discard packets that match this rule, and try to send an ICMPv6
1105 unreachable notice with code
1109 is a number from 0, 1, 3 or 4, or one of these aliases:
1110 .Cm no-route, admin-prohib, address
1113 The search terminates.
1114 .It Cm netgraph Ar cookie
1115 Divert packet into netgraph with given
1117 The search terminates.
1118 If packet is later returned from netgraph it is either
1119 accepted or continues with the next rule, depending on
1120 .Va net.inet.ip.fw.one_pass
1122 .It Cm ngtee Ar cookie
1123 A copy of packet is diverted into netgraph, original
1124 packet continues with the next rule.
1127 for more information on
1132 .It Cm setfib Ar fibnum | tablearg
1133 The packet is tagged so as to use the FIB (routing table)
1135 in any subsequent forwarding decisions.
1136 In the current implementation, this is limited to the values 0 through 15, see
1138 Processing continues at the next rule.
1139 It is possible to use the
1141 keyword with setfib.
1142 If the tablearg value is not within the compiled range of fibs,
1143 the packet's fib is set to 0.
1144 .It Cm setdscp Ar DSCP | number | tablearg
1145 Set specified DiffServ codepoint for an IPv4/IPv6 packet.
1146 Processing continues at the next rule.
1147 Supported values are:
1195 Additionally, DSCP value can be specified by number (0..63).
1196 It is also possible to use the
1198 keyword with setdscp.
1199 If the tablearg value is not within the 0..63 range, lower 6 bits of supplied
1201 .It Cm tcp-setmss Ar mss
1202 Set the Maximum Segment Size (MSS) in the TCP segment to value
1206 should be loaded or kernel should have
1207 .Cm options IPFIREWALL_PMOD
1208 to be able use this action.
1209 This command does not change a packet if original MSS value is lower than
1211 Both TCP over IPv4 and over IPv6 are supported.
1212 Regardless of matched a packet or not by the
1214 rule, the search continues with the next rule.
1216 Queue and reassemble IPv4 fragments.
1217 If the packet is not fragmented, counters are updated and
1218 processing continues with the next rule.
1219 If the packet is the last logical fragment, the packet is reassembled and, if
1220 .Va net.inet.ip.fw.one_pass
1221 is set to 0, processing continues with the next rule.
1222 Otherwise, the packet is allowed to pass and the search terminates.
1223 If the packet is a fragment in the middle of a logical group of fragments,
1225 processing stops immediately.
1227 Fragment handling can be tuned via
1228 .Va net.inet.ip.maxfragpackets
1230 .Va net.inet.ip.maxfragsperpacket
1231 which limit, respectively, the maximum number of processable
1232 fragments (default: 800) and
1233 the maximum number of fragments per packet (default: 16).
1235 NOTA BENE: since fragments do not contain port numbers,
1236 they should be avoided with the
1239 Alternatively, direction-based (like
1243 ) and source-based (like
1245 ) match patterns can be used to select fragments.
1247 Usually a simple rule like:
1248 .Bd -literal -offset indent
1249 # reassemble incoming fragments
1250 ipfw add reass all from any to any in
1253 is all you need at the beginning of your ruleset.
1255 Discard packets that match this rule, and if the packet is an SCTP packet,
1256 try to send an SCTP packet containing an ABORT chunk.
1257 The search terminates.
1259 Discard packets that match this rule, and if the packet is an SCTP packet,
1260 try to send an SCTP packet containing an ABORT chunk.
1261 The search terminates.
1264 The body of a rule contains zero or more patterns (such as
1265 specific source and destination addresses or ports,
1266 protocol options, incoming or outgoing interfaces, etc.)
1267 that the packet must match in order to be recognised.
1268 In general, the patterns are connected by (implicit)
1270 operators -- i.e., all must match in order for the
1272 Individual patterns can be prefixed by the
1274 operator to reverse the result of the match, as in
1276 .Dl "ipfw add 100 allow ip from not 1.2.3.4 to any"
1278 Additionally, sets of alternative match patterns
1280 can be constructed by putting the patterns in
1281 lists enclosed between parentheses ( ) or braces { }, and
1284 operator as follows:
1286 .Dl "ipfw add 100 allow ip from { x or not y or z } to any"
1288 Only one level of parentheses is allowed.
1289 Beware that most shells have special meanings for parentheses
1290 or braces, so it is advisable to put a backslash \\ in front of them
1291 to prevent such interpretations.
1293 The body of a rule must in general include a source and destination
1297 can be used in various places to specify that the content of
1298 a required field is irrelevant.
1300 The rule body has the following format:
1301 .Bd -ragged -offset indent
1302 .Op Ar proto Cm from Ar src Cm to Ar dst
1306 The first part (proto from src to dst) is for backward
1307 compatibility with earlier versions of
1311 any match pattern (including MAC headers, IP protocols,
1312 addresses and ports) can be specified in the
1316 Rule fields have the following meaning:
1317 .Bl -tag -width indent
1318 .It Ar proto : protocol | Cm { Ar protocol Cm or ... }
1319 .It Ar protocol : Oo Cm not Oc Ar protocol-name | protocol-number
1320 An IP protocol specified by number or name
1321 (for a complete list see
1322 .Pa /etc/protocols ) ,
1323 or one of the following keywords:
1324 .Bl -tag -width indent
1326 Matches IPv4 packets.
1328 Matches IPv6 packets.
1337 option will be treated as inner protocol.
1345 .Cm { Ar protocol Cm or ... }
1348 is provided for convenience only but its use is deprecated.
1349 .It Ar src No and Ar dst : Bro Cm addr | Cm { Ar addr Cm or ... } Brc Op Oo Cm not Oc Ar ports
1350 An address (or a list, see below)
1351 optionally followed by
1357 with multiple addresses) is provided for convenience only and
1358 its use is discouraged.
1359 .It Ar addr : Oo Cm not Oc Bro
1360 .Cm any | me | me6 |
1361 .Cm table Ns Pq Ar name Ns Op , Ns Ar value
1362 .Ar | addr-list | addr-set
1364 .Bl -tag -width indent
1366 Matches any IP address.
1368 Matches any IP address configured on an interface in the system.
1370 Matches any IPv6 address configured on an interface in the system.
1371 The address list is evaluated at the time the packet is
1373 .It Cm table Ns Pq Ar name Ns Op , Ns Ar value
1374 Matches any IPv4 or IPv6 address for which an entry exists in the lookup table
1376 If an optional 32-bit unsigned
1378 is also specified, an entry will match only if it has this value.
1381 section below for more information on lookup tables.
1383 .It Ar addr-list : ip-addr Ns Op Ns , Ns Ar addr-list
1385 A host or subnet address specified in one of the following ways:
1386 .Bl -tag -width indent
1387 .It Ar numeric-ip | hostname
1388 Matches a single IPv4 address, specified as dotted-quad or a hostname.
1389 Hostnames are resolved at the time the rule is added to the firewall list.
1390 .It Ar addr Ns / Ns Ar masklen
1391 Matches all addresses with base
1393 (specified as an IP address, a network number, or a hostname)
1397 As an example, 1.2.3.4/25 or 1.2.3.0/25 will match
1398 all IP numbers from 1.2.3.0 to 1.2.3.127 .
1399 .It Ar addr Ns : Ns Ar mask
1400 Matches all addresses with base
1402 (specified as an IP address, a network number, or a hostname)
1405 specified as a dotted quad.
1406 As an example, 1.2.3.4:255.0.255.0 or 1.0.3.0:255.0.255.0 will match
1408 This form is advised only for non-contiguous
1410 It is better to resort to the
1411 .Ar addr Ns / Ns Ar masklen
1412 format for contiguous masks, which is more compact and less
1415 .It Ar addr-set : addr Ns Oo Ns / Ns Ar masklen Oc Ns Cm { Ns Ar list Ns Cm }
1416 .It Ar list : Bro Ar num | num-num Brc Ns Op Ns , Ns Ar list
1417 Matches all addresses with base address
1419 (specified as an IP address, a network number, or a hostname)
1420 and whose last byte is in the list between braces { } .
1421 Note that there must be no spaces between braces and
1422 numbers (spaces after commas are allowed).
1423 Elements of the list can be specified as single entries
1427 field is used to limit the size of the set of addresses,
1428 and can have any value between 24 and 32.
1430 it will be assumed as 24.
1432 This format is particularly useful to handle sparse address sets
1433 within a single rule.
1434 Because the matching occurs using a
1435 bitmask, it takes constant time and dramatically reduces
1436 the complexity of rulesets.
1438 As an example, an address specified as 1.2.3.4/24{128,35-55,89}
1439 or 1.2.3.0/24{128,35-55,89}
1440 will match the following IP addresses:
1442 1.2.3.128, 1.2.3.35 to 1.2.3.55, 1.2.3.89 .
1443 .It Ar addr6-list : ip6-addr Ns Op Ns , Ns Ar addr6-list
1445 A host or subnet specified one of the following ways:
1446 .Bl -tag -width indent
1447 .It Ar numeric-ip | hostname
1448 Matches a single IPv6 address as allowed by
1451 Hostnames are resolved at the time the rule is added to the firewall
1453 .It Ar addr Ns / Ns Ar masklen
1454 Matches all IPv6 addresses with base
1456 (specified as allowed by
1462 .It Ar addr Ns / Ns Ar mask
1463 Matches all IPv6 addresses with base
1465 (specified as allowed by
1470 specified as allowed by
1472 As an example, fe::640:0:0/ffff::ffff:ffff:0:0 will match
1474 This form is advised only for non-contiguous
1476 It is better to resort to the
1477 .Ar addr Ns / Ns Ar masklen
1478 format for contiguous masks, which is more compact and less
1482 No support for sets of IPv6 addresses is provided because IPv6 addresses
1483 are typically random past the initial prefix.
1484 .It Ar ports : Bro Ar port | port Ns \&- Ns Ar port Ns Brc Ns Op , Ns Ar ports
1485 For protocols which support port numbers (such as SCTP, TCP and UDP), optional
1487 may be specified as one or more ports or port ranges, separated
1488 by commas but no spaces, and an optional
1493 notation specifies a range of ports (including boundaries).
1497 may be used instead of numeric port values.
1498 The length of the port list is limited to 30 ports or ranges,
1499 though one can specify larger ranges by using an
1503 section of the rule.
1507 can be used to escape the dash
1509 character in a service name (from a shell, the backslash must be
1510 typed twice to avoid the shell itself interpreting it as an escape
1513 .Dl "ipfw add count tcp from any ftp\e\e-data-ftp to any"
1515 Fragmented packets which have a non-zero offset (i.e., not the first
1516 fragment) will never match a rule which has one or more port
1520 option for details on matching fragmented packets.
1522 .Ss RULE OPTIONS (MATCH PATTERNS)
1523 Additional match patterns can be used within
1525 Zero or more of these so-called
1527 can be present in a rule, optionally prefixed by the
1529 operand, and possibly grouped into
1532 The following match patterns can be used (listed in alphabetical order):
1533 .Bl -tag -width indent
1534 .It Cm // this is a comment .
1535 Inserts the specified text as a comment in the rule.
1536 Everything following // is considered as a comment and stored in the rule.
1537 You can have comment-only rules, which are listed as having a
1539 action followed by the comment.
1543 .It Cm defer-immediate-action | defer-action
1544 A rule with this option will not perform normal action
1546 This option is intended to be used with
1550 as the dynamic rule, created but ignored on match, will work
1555 .Cm defer-immediate-action
1556 create a dynamic rule and continue with the next rule without actually
1557 performing the action part of this rule.
1558 When the rule is later activated via the state table, the action is
1561 Matches only packets generated by a divert socket.
1562 .It Cm diverted-loopback
1563 Matches only packets coming from a divert socket back into the IP stack
1565 .It Cm diverted-output
1566 Matches only packets going from a divert socket back outward to the IP
1567 stack output for delivery.
1568 .It Cm dst-ip Ar ip-address
1569 Matches IPv4 packets whose destination IP is one of the address(es)
1570 specified as argument.
1571 .It Bro Cm dst-ip6 | dst-ipv6 Brc Ar ip6-address
1572 Matches IPv6 packets whose destination IP is one of the address(es)
1573 specified as argument.
1574 .It Cm dst-port Ar ports
1575 Matches IP packets whose destination port is one of the port(s)
1576 specified as argument.
1578 Matches TCP packets that have the RST or ACK bits set.
1579 .It Cm ext6hdr Ar header
1580 Matches IPv6 packets containing the extended header given by
1582 Supported headers are:
1588 any type of Routing Header
1590 Source routing Routing Header Type 0
1592 Mobile IPv6 Routing Header Type 2
1596 IPSec authentication headers
1598 and IPsec encapsulated security payload headers
1600 .It Cm fib Ar fibnum
1601 Matches a packet that has been tagged to use
1602 the given FIB (routing table) number.
1603 .It Cm flow Ar table Ns Pq Ar name Ns Op , Ns Ar value
1604 Search for the flow entry in lookup table
1606 If not found, the match fails.
1607 Otherwise, the match succeeds and
1609 is set to the value extracted from the table.
1611 This option can be useful to quickly dispatch traffic based on
1612 certain packet fields.
1615 section below for more information on lookup tables.
1616 .It Cm flow-id Ar labels
1617 Matches IPv6 packets containing any of the flow labels given in
1620 is a comma separated list of numeric flow labels.
1621 .It Cm dst-mac Ar table Ns Pq Ar name Ns Op , Ns Ar value
1622 Search for the destination MAC address entry in lookup table
1624 If not found, the match fails.
1625 Otherwise, the match succeeds and
1627 is set to the value extracted from the table.
1628 .It Cm src-mac Ar table Ns Pq Ar name Ns Op , Ns Ar value
1629 Search for the source MAC address entry in lookup table
1631 If not found, the match fails.
1632 Otherwise, the match succeeds and
1634 is set to the value extracted from the table.
1636 Matches IPv4 packets whose
1638 field contains the comma separated list of IPv4 fragmentation
1639 options specified in
1641 The recognized options are:
1643 .Pq Dv don't fragment ,
1645 .Pq Dv more fragments ,
1647 .Pq Dv reserved fragment bit
1649 .Pq Dv non-zero fragment offset .
1650 The absence of a particular options may be denoted
1654 Empty list of options defaults to matching on non-zero fragment offset.
1655 Such rule would match all not the first fragment datagrams,
1657 This is a backward compatibility with older rulesets.
1659 Matches all TCP or UDP packets sent by or received for a
1663 may be specified by name or number.
1665 Matches all TCP or UDP packets sent by or received for the
1666 jail whose ID or name is
1668 .It Cm icmptypes Ar types
1669 Matches ICMP packets whose ICMP type is in the list
1671 The list may be specified as any combination of
1672 individual types (numeric) separated by commas.
1673 .Em Ranges are not allowed .
1674 The supported ICMP types are:
1678 destination unreachable
1686 router advertisement
1690 time-to-live exceeded
1702 address mask request
1704 and address mask reply
1706 .It Cm icmp6types Ar types
1707 Matches ICMP6 packets whose ICMP6 type is in the list of
1709 The list may be specified as any combination of
1710 individual types (numeric) separated by commas.
1711 .Em Ranges are not allowed .
1713 Matches incoming or outgoing packets, respectively.
1717 are mutually exclusive (in fact,
1721 .It Cm ipid Ar id-list
1722 Matches IPv4 packets whose
1724 field has value included in
1726 which is either a single value or a list of values or ranges
1727 specified in the same way as
1729 .It Cm iplen Ar len-list
1730 Matches IP packets whose total length, including header and data, is
1733 which is either a single value or a list of values or ranges
1734 specified in the same way as
1736 .It Cm ipoptions Ar spec
1737 Matches packets whose IPv4 header contains the comma separated list of
1738 options specified in
1740 The supported IP options are:
1743 (strict source route),
1745 (loose source route),
1747 (record packet route) and
1750 The absence of a particular option may be denoted
1753 .It Cm ipprecedence Ar precedence
1754 Matches IPv4 packets whose precedence field is equal to
1757 Matches packets that have IPSEC history associated with them
1758 (i.e., the packet comes encapsulated in IPSEC, the kernel
1759 has IPSEC support, and can correctly decapsulate it).
1761 Note that specifying
1763 is different from specifying
1765 as the latter will only look at the specific IP protocol field,
1766 irrespective of IPSEC kernel support and the validity of the IPSEC data.
1768 Further note that this flag is silently ignored in kernels without
1770 It does not affect rule processing when given and the
1771 rules are handled as if with no
1774 .It Cm iptos Ar spec
1775 Matches IPv4 packets whose
1777 field contains the comma separated list of
1778 service types specified in
1780 The supported IP types of service are:
1783 .Pq Dv IPTOS_LOWDELAY ,
1785 .Pq Dv IPTOS_THROUGHPUT ,
1787 .Pq Dv IPTOS_RELIABILITY ,
1789 .Pq Dv IPTOS_MINCOST ,
1791 .Pq Dv IPTOS_ECN_CE .
1792 The absence of a particular type may be denoted
1795 .It Cm dscp spec Ns Op , Ns Ar spec
1796 Matches IPv4/IPv6 packets whose
1798 field value is contained in
1801 Multiple values can be specified via
1802 the comma separated list.
1803 Value can be one of keywords used in
1805 action or exact number.
1806 .It Cm ipttl Ar ttl-list
1807 Matches IPv4 packets whose time to live is included in
1809 which is either a single value or a list of values or ranges
1810 specified in the same way as
1812 .It Cm ipversion Ar ver
1813 Matches IP packets whose IP version field is
1815 .It Cm keep-state Op Ar :flowname
1816 Upon a match, the firewall will create a dynamic rule, whose
1817 default behaviour is to match bidirectional traffic between
1818 source and destination IP/port using the same protocol.
1819 The rule has a limited lifetime (controlled by a set of
1821 variables), and the lifetime is refreshed every time a matching
1825 is used to assign additional to addresses, ports and protocol parameter
1827 It can be used for more accurate matching by
1832 keyword is special name used for compatibility with old rulesets.
1834 Matches only layer2 packets, i.e., those passed to
1839 .Fn ether_output_frame .
1840 .It Cm limit Bro Cm src-addr | src-port | dst-addr | dst-port Brc Ar N Op Ar :flowname
1841 The firewall will only allow
1843 connections with the same
1844 set of parameters as specified in the rule.
1846 of source and destination addresses and ports can be
1848 .It Cm lookup Bro Cm dst-ip | dst-port | dst-mac | src-ip | src-port | src-mac | uid | jail Brc Ar name
1849 Search an entry in lookup table
1851 that matches the field specified as argument.
1852 If not found, the match fails.
1853 Otherwise, the match succeeds and
1855 is set to the value extracted from the table.
1857 This option can be useful to quickly dispatch traffic based on
1858 certain packet fields.
1861 section below for more information on lookup tables.
1862 .It Cm { MAC | mac } Ar dst-mac src-mac
1863 Match packets with a given
1867 addresses, specified as the
1869 keyword (matching any MAC address), or six groups of hex digits
1870 separated by colons,
1871 and optionally followed by a mask indicating the significant bits.
1872 The mask may be specified using either of the following methods:
1873 .Bl -enum -width indent
1877 followed by the number of significant bits.
1878 For example, an address with 33 significant bits could be specified as:
1880 .Dl "MAC 10:20:30:40:50:60/33 any"
1884 followed by a bitmask specified as six groups of hex digits separated
1886 For example, an address in which the last 16 bits are significant could
1889 .Dl "MAC 10:20:30:40:50:60&00:00:00:00:ff:ff any"
1891 Note that the ampersand character has a special meaning in many shells
1892 and should generally be escaped.
1894 Note that the order of MAC addresses (destination first,
1896 the same as on the wire, but the opposite of the one used for
1898 .It Cm mac-type Ar mac-type
1899 Matches packets whose Ethernet Type field
1900 corresponds to one of those specified as argument.
1902 is specified in the same way as
1904 (i.e., one or more comma-separated single values or ranges).
1905 You can use symbolic names for known values such as
1906 .Em vlan , ipv4, ipv6 .
1907 Values can be entered as decimal or hexadecimal (if prefixed by 0x),
1908 and they are always printed as hexadecimal (unless the
1910 option is used, in which case symbolic resolution will be attempted).
1911 .It Cm proto Ar protocol
1912 Matches packets with the corresponding IP protocol.
1914 Upon a match, the firewall will create a dynamic rule as if
1917 However, this option doesn't imply an implicit
1921 .It Cm recv | xmit | via Brq Ar ifX | Ar if Ns Cm * | Ar table Ns Po Ar name Ns Oo , Ns Ar value Oc Pc | Ar ipno | Ar any
1922 Matches packets received, transmitted or going through,
1923 respectively, the interface specified by exact name
1927 by IP address, or through some interface.
1930 may be used to match interface by its kernel ifindex.
1933 section below for more information on lookup tables.
1937 keyword causes the interface to always be checked.
1944 then only the receive or transmit interface (respectively)
1946 By specifying both, it is possible to match packets based on
1947 both receive and transmit interface, e.g.:
1949 .Dl "ipfw add deny ip from any to any out recv ed0 xmit ed1"
1953 interface can be tested on either incoming or outgoing packets,
1956 interface can only be tested on outgoing packets.
1961 is invalid) whenever
1965 A packet might not have a receive or transmit interface: packets
1966 originating from the local host have no receive interface,
1967 while packets destined for the local host have no transmit
1969 .It Cm set-limit Bro Cm src-addr | src-port | dst-addr | dst-port Brc Ar N
1972 but does not have an implicit
1976 Matches TCP packets that have the SYN bit set but no ACK bit.
1977 This is the short form of
1978 .Dq Li tcpflags\ syn,!ack .
1980 Matches packets that are associated to a local socket and
1981 for which the SO_USER_COOKIE socket option has been set
1982 to a non-zero value.
1983 As a side effect, the value of the
1984 option is made available as
1986 value, which in turn can be used as
1991 .It Cm src-ip Ar ip-address
1992 Matches IPv4 packets whose source IP is one of the address(es)
1993 specified as an argument.
1994 .It Cm src-ip6 Ar ip6-address
1995 Matches IPv6 packets whose source IP is one of the address(es)
1996 specified as an argument.
1997 .It Cm src-port Ar ports
1998 Matches IP packets whose source port is one of the port(s)
1999 specified as argument.
2000 .It Cm tagged Ar tag-list
2001 Matches packets whose tags are included in
2003 which is either a single value or a list of values or ranges
2004 specified in the same way as
2006 Tags can be applied to the packet using
2008 rule action parameter (see it's description for details on tags).
2009 .It Cm tcpack Ar ack
2011 Match if the TCP header acknowledgment number field is set to
2013 .It Cm tcpdatalen Ar tcpdatalen-list
2014 Matches TCP packets whose length of TCP data is
2015 .Ar tcpdatalen-list ,
2016 which is either a single value or a list of values or ranges
2017 specified in the same way as
2019 .It Cm tcpflags Ar spec
2021 Match if the TCP header contains the comma separated list of
2024 The supported TCP flags are:
2033 The absence of a particular flag may be denoted
2036 A rule which contains a
2038 specification can never match a fragmented packet which has
2042 option for details on matching fragmented packets.
2043 .It Cm tcpmss Ar tcpmss-list
2044 Matches TCP packets whose MSS (maximum segment size) value is set to
2046 which is either a single value or a list of values or ranges
2047 specified in the same way as
2049 .It Cm tcpseq Ar seq
2051 Match if the TCP header sequence number field is set to
2053 .It Cm tcpwin Ar tcpwin-list
2054 Matches TCP packets whose header window field is set to
2056 which is either a single value or a list of values or ranges
2057 specified in the same way as
2059 .It Cm tcpoptions Ar spec
2061 Match if the TCP header contains the comma separated list of
2062 options specified in
2064 The supported TCP options are:
2067 (maximum segment size),
2069 (tcp window advertisement),
2073 (rfc1323 timestamp) and
2075 (rfc1644 t/tcp connection count).
2076 The absence of a particular option may be denoted
2080 Match all TCP or UDP packets sent by or received for a
2084 may be matched by name or identification number.
2086 For incoming packets,
2087 a routing table lookup is done on the packet's source address.
2088 If the interface on which the packet entered the system matches the
2089 outgoing interface for the route,
2091 If the interfaces do not match up,
2092 the packet does not match.
2093 All outgoing packets or packets with no incoming interface match.
2095 The name and functionality of the option is intentionally similar to
2096 the Cisco IOS command:
2098 .Dl ip verify unicast reverse-path
2100 This option can be used to make anti-spoofing rules to reject all
2101 packets with source addresses not from this interface.
2105 For incoming packets,
2106 a routing table lookup is done on the packet's source address.
2107 If a route to the source address exists, but not the default route
2108 or a blackhole/reject route, the packet matches.
2109 Otherwise, the packet does not match.
2110 All outgoing packets match.
2112 The name and functionality of the option is intentionally similar to
2113 the Cisco IOS command:
2115 .Dl ip verify unicast source reachable-via any
2117 This option can be used to make anti-spoofing rules to reject all
2118 packets whose source address is unreachable.
2120 For incoming packets, the packet's source address is checked if it
2121 belongs to a directly connected network.
2122 If the network is directly connected, then the interface the packet
2123 came on in is compared to the interface the network is connected to.
2124 When incoming interface and directly connected interface are not the
2125 same, the packet does not match.
2126 Otherwise, the packet does match.
2127 All outgoing packets match.
2129 This option can be used to make anti-spoofing rules to reject all
2130 packets that pretend to be from a directly connected network but do
2131 not come in through that interface.
2132 This option is similar to but more restricted than
2134 because it engages only on packets with source addresses of directly
2135 connected networks instead of all source addresses.
2138 Lookup tables are useful to handle large sparse sets of
2139 addresses or other search keys (e.g., ports, jail IDs, interface names).
2140 In the rest of this section we will use the term ``key''.
2141 Table name needs to match the following spec:
2143 Tables with the same name can be created in different
2145 However, rule links to the tables in
2148 This behavior can be controlled by
2149 .Va net.inet.ip.fw.tables_sets
2153 section for more information.
2154 There may be up to 65535 different lookup tables.
2156 The following table types are supported:
2157 .Bl -tag -width indent
2158 .It Ar table-type : Ar addr | iface | number | flow | mac
2159 .It Ar table-key : Ar addr Ns Oo / Ns Ar masklen Oc | iface-name | number | flow-spec
2160 .It Ar flow-spec : Ar flow-field Ns Op , Ns Ar flow-spec
2161 .It Ar flow-field : src-ip | proto | src-port | dst-ip | dst-port
2163 Matches IPv4 or IPv6 address.
2164 Each entry is represented by an
2165 .Ar addr Ns Op / Ns Ar masklen
2166 and will match all addresses with base
2168 (specified as an IPv4/IPv6 address, or a hostname) and mask width of
2173 is not specified, it defaults to 32 for IPv4 and 128 for IPv6.
2174 When looking up an IP address in a table, the most specific
2177 Matches interface names.
2178 Each entry is represented by string treated as interface name.
2179 Wildcards are not supported.
2181 Matches protocol ports, uids/gids or jail IDs.
2182 Each entry is represented by 32-bit unsigned integer.
2183 Ranges are not supported.
2185 Matches packet fields specified by
2187 type suboptions with table entries.
2189 Matches MAC address.
2190 Each entry is represented by an
2191 .Ar addr Ns Op / Ns Ar masklen
2192 and will match all addresses with base
2199 is not specified, it defaults to 48.
2200 When looking up an MAC address in a table, the most specific
2204 Tables require explicit creation via
2208 The following creation options are supported:
2209 .Bl -tag -width indent
2210 .It Ar create-options : Ar create-option | create-options
2211 .It Ar create-option : Cm type Ar table-type | Cm valtype Ar value-mask | Cm algo Ar algo-desc |
2212 .Cm limit Ar number | Cm locked | Cm missing | Cm or-flush
2218 Table algorithm to use (see below).
2220 Maximum number of items that may be inserted into table.
2222 Restrict any table modifications.
2224 Do not fail if table already exists and has exactly same options as new one.
2226 Flush existing table with same name instead of returning error.
2229 so existing table must be compatible with new one.
2232 Some of these options may be modified later via
2235 The following options can be changed:
2236 .Bl -tag -width indent
2237 .It Ar modify-options : Ar modify-option | modify-options
2238 .It Ar modify-option : Cm limit Ar number
2240 Alter maximum number of items that may be inserted into table.
2243 Additionally, table can be locked or unlocked using
2251 can be swapped with each other using
2254 Swap may fail if tables limits are set and data exchange
2255 would result in limits hit.
2256 Operation is performed atomically.
2258 One or more entries can be added to a table at once using
2261 Addition of all items are performed atomically.
2262 By default, error in addition of one entry does not influence
2263 addition of other entries.
2264 However, non-zero error code is returned in that case.
2267 keyword may be specified before
2269 to indicate all-or-none add request.
2271 One or more entries can be removed from a table at once using
2274 By default, error in removal of one entry does not influence
2275 removing of other entries.
2276 However, non-zero error code is returned in that case.
2278 It may be possible to check what entry will be found on particular
2284 This functionality is optional and may be unsupported in some algorithms.
2286 The following operations can be performed on
2291 .Bl -tag -width indent
2295 Removes all entries.
2297 Shows generic table information.
2299 Shows generic table information and algo-specific data.
2302 The following lookup algorithms are supported:
2303 .Bl -tag -width indent
2304 .It Ar algo-desc : algo-name | "algo-name algo-data"
2305 .It Ar algo-name : Ar addr: radix | addr: hash | iface: array | number: array | flow: hash | mac: radix
2307 Separate Radix trees for IPv4 and IPv6, the same way as the routing table (see
2313 Separate auto-growing hashes for IPv4 and IPv6.
2314 Accepts entries with the same mask length specified initially via
2315 .Cm "addr:hash masks=/v4,/v6"
2316 algorithm creation options.
2317 Assume /32 and /128 masks by default.
2318 Search removes host bits (according to mask) from supplied address and checks
2319 resulting key in appropriate hash.
2320 Mostly optimized for /64 and byte-ranged IPv6 masks.
2322 Array storing sorted indexes for entries which are presented in the system.
2323 Optimized for very fast lookup.
2325 Array storing sorted u32 numbers.
2327 Auto-growing hash storing flow entries.
2328 Search calculates hash on required packet fields and searches for matching
2329 entries in selected bucket.
2331 Radix tree for MAC address
2336 feature provides the ability to use a value, looked up in the table, as
2337 the argument for a rule action, action parameter or rule option.
2338 This can significantly reduce number of rules in some configurations.
2339 If two tables are used in a rule, the result of the second (destination)
2342 Each record may hold one or more values according to
2344 This mask is set on table creation via
2347 The following value types are supported:
2348 .Bl -tag -width indent
2349 .It Ar value-mask : Ar value-type Ns Op , Ns Ar value-mask
2350 .It Ar value-type : Ar skipto | pipe | fib | nat | dscp | tag | divert |
2351 .Ar netgraph | limit | ipv4
2353 rule number to jump to.
2357 fib number to match/set.
2359 nat number to jump to.
2361 dscp value to match/set.
2363 tag number to match/set.
2365 port number to divert traffic to.
2367 hook number to move packet to.
2369 maximum number of connections.
2371 IPv4 nexthop to fwd packets to.
2373 IPv6 nexthop to fwd packets to.
2378 argument can be used with the following actions:
2379 .Cm nat, pipe, queue, divert, tee, netgraph, ngtee, fwd, skipto, setfib ,
2387 action, the user should be aware that the code will walk the ruleset
2388 up to a rule equal to, or past, the given number.
2392 Section for example usage of tables and the tablearg keyword.
2394 Each rule or table belongs to one of 32 different
2397 Set 31 is reserved for the default rule.
2399 By default, rules or tables are put in set 0, unless you use the
2401 attribute when adding a new rule or table.
2402 Sets can be individually and atomically enabled or disabled,
2403 so this mechanism permits an easy way to store multiple configurations
2404 of the firewall and quickly (and atomically) switch between them.
2406 By default, tables from set 0 are referenced when adding rule with
2407 table opcodes regardless of rule set.
2408 This behavior can be changed by setting
2409 .Va net.inet.ip.fw.tables_sets
2411 Rule's set will then be used for table references.
2413 The command to enable/disable sets is
2414 .Bd -ragged -offset indent
2416 .Cm set Oo Cm disable Ar number ... Oc Op Cm enable Ar number ...
2423 sections can be specified.
2424 Command execution is atomic on all the sets specified in the command.
2425 By default, all sets are enabled.
2427 When you disable a set, its rules behave as if they do not exist
2428 in the firewall configuration, with only one exception:
2429 .Bd -ragged -offset indent
2430 dynamic rules created from a rule before it had been disabled
2431 will still be active until they expire.
2433 dynamic rules you have to explicitly delete the parent rule
2434 which generated them.
2437 The set number of rules can be changed with the command
2438 .Bd -ragged -offset indent
2441 .Brq Cm rule Ar rule-number | old-set
2445 Also, you can atomically swap two rulesets with the command
2446 .Bd -ragged -offset indent
2448 .Cm set swap Ar first-set second-set
2453 Section on some possible uses of sets of rules.
2454 .Sh STATEFUL FIREWALL
2455 Stateful operation is a way for the firewall to dynamically
2456 create rules for specific flows when packets that
2457 match a given pattern are detected.
2458 Support for stateful
2459 operation comes through the
2460 .Cm check-state , keep-state , record-state , limit
2466 Dynamic rules are created when a packet matches a
2472 rule, causing the creation of a
2474 rule which will match all and only packets with
2478 .Em src-ip/src-port dst-ip/dst-port
2483 are used here only to denote the initial match addresses, but they
2484 are completely equivalent afterwards).
2490 This name is used in matching together with addresses, ports and protocol.
2491 Dynamic rules will be checked at the first
2492 .Cm check-state, keep-state
2495 occurrence, and the action performed upon a match will be the same
2496 as in the parent rule.
2498 Note that no additional attributes other than protocol and IP addresses
2499 and ports and :flowname are checked on dynamic rules.
2501 The typical use of dynamic rules is to keep a closed firewall configuration,
2502 but let the first TCP SYN packet from the inside network install a
2503 dynamic rule for the flow so that packets belonging to that session
2504 will be allowed through the firewall:
2506 .Dl "ipfw add check-state :OUTBOUND"
2507 .Dl "ipfw add allow tcp from my-subnet to any setup keep-state :OUTBOUND"
2508 .Dl "ipfw add deny tcp from any to any"
2510 A similar approach can be used for UDP, where an UDP packet coming
2511 from the inside will install a dynamic rule to let the response through
2514 .Dl "ipfw add check-state :OUTBOUND"
2515 .Dl "ipfw add allow udp from my-subnet to any keep-state :OUTBOUND"
2516 .Dl "ipfw add deny udp from any to any"
2518 Dynamic rules expire after some time, which depends on the status
2519 of the flow and the setting of some
2523 .Sx SYSCTL VARIABLES
2525 For TCP sessions, dynamic rules can be instructed to periodically
2526 send keepalive packets to refresh the state of the rule when it is
2531 for more examples on how to use dynamic rules.
2532 .Sh TRAFFIC SHAPER (DUMMYNET) CONFIGURATION
2534 is also the user interface for the
2536 traffic shaper, packet scheduler and network emulator, a subsystem that
2537 can artificially queue, delay or drop packets
2538 emulating the behaviour of certain network links
2539 or queueing systems.
2542 operates by first using the firewall to select packets
2543 using any match pattern that can be used in
2546 Matching packets are then passed to either of two
2547 different objects, which implement the traffic regulation:
2548 .Bl -hang -offset XXXX
2554 with given bandwidth and propagation delay,
2555 driven by a FIFO scheduler and a single queue with programmable
2556 queue size and packet loss rate.
2557 Packets are appended to the queue as they come out from
2559 and then transferred in FIFO order to the link at the desired rate.
2563 is an abstraction used to implement packet scheduling
2564 using one of several packet scheduling algorithms.
2567 are first grouped into flows according to a mask on the 5-tuple.
2568 Flows are then passed to the scheduler associated to the
2570 and each flow uses scheduling parameters (weight and others)
2571 as configured in the
2574 A scheduler in turn is connected to an emulated link,
2575 and arbitrates the link's bandwidth among backlogged flows according to
2576 weights and to the features of the scheduling algorithm in use.
2581 can be used to set hard limits to the bandwidth that a flow can use, whereas
2583 can be used to determine how different flows share the available bandwidth.
2585 A graphical representation of the binding of queues,
2586 flows, schedulers and links is below.
2587 .Bd -literal -offset indent
2588 (flow_mask|sched_mask) sched_mask
2589 +---------+ weight Wx +-------------+
2590 | |->-[flow]-->--| |-+
2591 -->--| QUEUE x | ... | | |
2592 | |->-[flow]-->--| SCHEDuler N | |
2594 ... | +--[LINK N]-->--
2595 +---------+ weight Wy | | +--[LINK N]-->--
2596 | |->-[flow]-->--| | |
2597 -->--| QUEUE y | ... | | |
2598 | |->-[flow]-->--| | |
2599 +---------+ +-------------+ |
2602 It is important to understand the role of the SCHED_MASK
2603 and FLOW_MASK, which are configured through the commands
2604 .Dl "ipfw sched N config mask SCHED_MASK ..."
2606 .Dl "ipfw queue X config mask FLOW_MASK ..." .
2608 The SCHED_MASK is used to assign flows to one or more
2609 scheduler instances, one for each
2610 value of the packet's 5-tuple after applying SCHED_MASK.
2611 As an example, using ``src-ip 0xffffff00'' creates one instance
2612 for each /24 destination subnet.
2614 The FLOW_MASK, together with the SCHED_MASK, is used to split
2616 As an example, using
2617 ``src-ip 0x000000ff''
2618 together with the previous SCHED_MASK makes a flow for
2619 each individual source address.
2620 In turn, flows for each /24
2621 subnet will be sent to the same scheduler instance.
2623 The above diagram holds even for the
2625 case, with the only restriction that a
2627 only supports a SCHED_MASK, and forces the use of a FIFO
2628 scheduler (these are for backward compatibility reasons;
2629 in fact, internally, a
2631 pipe is implemented exactly as above).
2633 There are two modes of
2641 mode tries to emulate a real link: the
2643 scheduler ensures that the packet will not leave the pipe faster than it
2644 would on the real link with a given bandwidth.
2647 mode allows certain packets to bypass the
2649 scheduler (if packet flow does not exceed pipe's bandwidth).
2650 This is the reason why the
2652 mode requires less CPU cycles per packet (on average) and packet latency
2653 can be significantly lower in comparison to a real link with the same
2659 mode can be enabled by setting the
2660 .Va net.inet.ip.dummynet.io_fast
2662 variable to a non-zero value.
2663 .Ss PIPE, QUEUE AND SCHEDULER CONFIGURATION
2669 configuration commands are the following:
2670 .Bd -ragged -offset indent
2671 .Cm pipe Ar number Cm config Ar pipe-configuration
2673 .Cm queue Ar number Cm config Ar queue-configuration
2675 .Cm sched Ar number Cm config Ar sched-configuration
2678 The following parameters can be configured for a pipe:
2680 .Bl -tag -width indent -compact
2681 .It Cm bw Ar bandwidth | device
2682 Bandwidth, measured in
2685 .Brq Cm bit/s | Byte/s .
2688 A value of 0 (default) means unlimited bandwidth.
2689 The unit must immediately follow the number, as in
2691 .Dl "dnctl pipe 1 config bw 300Kbit/s"
2693 If a device name is specified instead of a numeric value, as in
2695 .Dl "dnctl pipe 1 config bw tun0"
2697 then the transmit clock is supplied by the specified device.
2698 At the moment only the
2700 device supports this
2701 functionality, for use in conjunction with
2704 .It Cm delay Ar ms-delay
2705 Propagation delay, measured in milliseconds.
2706 The value is rounded to the next multiple of the clock tick
2707 (typically 10ms, but it is a good practice to run kernels
2709 .Dq "options HZ=1000"
2711 the granularity to 1ms or less).
2712 The default value is 0, meaning no delay.
2714 .It Cm burst Ar size
2715 If the data to be sent exceeds the pipe's bandwidth limit
2716 (and the pipe was previously idle), up to
2718 bytes of data are allowed to bypass the
2720 scheduler, and will be sent as fast as the physical link allows.
2721 Any additional data will be transmitted at the rate specified
2725 The burst size depends on how long the pipe has been idle;
2726 the effective burst size is calculated as follows:
2733 .It Cm profile Ar filename
2734 A file specifying the additional overhead incurred in the transmission
2735 of a packet on the link.
2737 Some link types introduce extra delays in the transmission
2738 of a packet, e.g., because of MAC level framing, contention on
2739 the use of the channel, MAC level retransmissions and so on.
2740 From our point of view, the channel is effectively unavailable
2741 for this extra time, which is constant or variable depending
2743 Additionally, packets may be dropped after this
2744 time (e.g., on a wireless link after too many retransmissions).
2745 We can model the additional delay with an empirical curve
2746 that represents its distribution.
2747 .Bd -literal -offset indent
2748 cumulative probability
2758 +-------*------------------->
2761 The empirical curve may have both vertical and horizontal lines.
2762 Vertical lines represent constant delay for a range of
2764 Horizontal lines correspond to a discontinuity in the delay
2765 distribution: the pipe will use the largest delay for a
2768 The file format is the following, with whitespace acting as
2769 a separator and '#' indicating the beginning a comment:
2770 .Bl -tag -width indent
2771 .It Cm name Ar identifier
2772 optional name (listed by "dnctl pipe show")
2773 to identify the delay distribution;
2775 the bandwidth used for the pipe.
2776 If not specified here, it must be present
2777 explicitly as a configuration parameter for the pipe;
2778 .It Cm loss-level Ar L
2779 the probability above which packets are lost.
2780 (0.0 <= L <= 1.0, default 1.0 i.e., no loss);
2782 the number of samples used in the internal
2783 representation of the curve (2..1024; default 100);
2784 .It Cm "delay prob" | "prob delay"
2785 One of these two lines is mandatory and defines
2786 the format of the following lines with data points.
2788 2 or more lines representing points in the curve,
2789 with either delay or probability first, according
2790 to the chosen format.
2791 The unit for delay is milliseconds.
2792 Data points do not need to be sorted.
2793 Also, the number of actual lines can be different
2794 from the value of the "samples" parameter:
2796 utility will sort and interpolate
2797 the curve as needed.
2800 Example of a profile file:
2801 .Bd -literal -offset indent
2806 0 200 # minimum overhead is 200ms
2812 #configuration file end
2816 The following parameters can be configured for a queue:
2818 .Bl -tag -width indent -compact
2819 .It Cm pipe Ar pipe_nr
2820 Connects a queue to the specified pipe.
2821 Multiple queues (with the same or different weights) can be connected to
2822 the same pipe, which specifies the aggregate rate for the set of queues.
2824 .It Cm weight Ar weight
2825 Specifies the weight to be used for flows matching this queue.
2826 The weight must be in the range 1..100, and defaults to 1.
2829 The following case-insensitive parameters can be configured for a
2832 .Bl -tag -width indent -compact
2833 .It Cm type Ar {fifo | wf2q+ | rr | qfq | fq_codel | fq_pie}
2834 specifies the scheduling algorithm to use.
2835 .Bl -tag -width indent -compact
2837 is just a FIFO scheduler (which means that all packets
2838 are stored in the same queue as they arrive to the scheduler).
2839 FIFO has O(1) per-packet time complexity, with very low
2840 constants (estimate 60-80ns on a 2GHz desktop machine)
2841 but gives no service guarantees.
2843 implements the WF2Q+ algorithm, which is a Weighted Fair Queueing
2844 algorithm which permits flows to share bandwidth according to
2846 Note that weights are not priorities; even a flow
2847 with a minuscule weight will never starve.
2848 WF2Q+ has O(log N) per-packet processing cost, where N is the number
2849 of flows, and is the default algorithm used by previous versions
2852 implements the Deficit Round Robin algorithm, which has O(1) processing
2853 costs (roughly, 100-150ns per packet)
2854 and permits bandwidth allocation according to weights, but
2855 with poor service guarantees.
2857 implements the QFQ algorithm, which is a very fast variant of
2858 WF2Q+, with similar service guarantees and O(1) processing
2859 costs (roughly, 200-250ns per packet).
2861 implements the FQ-CoDel (FlowQueue-CoDel) scheduler/AQM algorithm, which
2862 uses a modified Deficit Round Robin scheduler to manage two lists of sub-queues
2863 (old sub-queues and new sub-queues) for providing brief periods of priority to
2864 lightweight or short burst flows.
2865 By default, the total number of sub-queues is 1024.
2866 FQ-CoDel's internal, dynamically
2867 created sub-queues are controlled by separate instances of CoDel AQM.
2869 implements the FQ-PIE (FlowQueue-PIE) scheduler/AQM algorithm, which similar to
2871 but uses per sub-queue PIE AQM instance to control the queue delay.
2875 inherits AQM parameters and options from
2879 inherits AQM parameters and options from
2882 Additionally, both of
2886 have shared scheduler parameters which are:
2887 .Bl -tag -width indent
2890 specifies the quantum (credit) of the scheduler.
2892 is the number of bytes a queue can serve before being moved to the tail
2894 The default is 1514 bytes, and the maximum acceptable value
2898 specifies the hard size limit (in unit of packets) of all queues managed by an
2899 instance of the scheduler.
2900 The default value of
2902 is 10240 packets, and the maximum acceptable value is 20480 packets.
2905 specifies the total number of flow queues (sub-queues) that fq_*
2906 creates and manages.
2907 By default, 1024 sub-queues are created when an instance
2908 of the fq_{codel/pie} scheduler is created.
2909 The maximum acceptable value is
2913 Note that any token after
2917 is considered a parameter for fq_{codel/pie}.
2918 So, ensure all scheduler
2919 configuration options not related to fq_{codel/pie} are written before
2924 In addition to the type, all parameters allowed for a pipe can also
2925 be specified for a scheduler.
2927 Finally, the following parameters can be configured for both
2930 .Bl -tag -width XXXX -compact
2931 .It Cm buckets Ar hash-table-size
2932 Specifies the size of the hash table used for storing the
2934 Default value is 64 controlled by the
2937 .Va net.inet.ip.dummynet.hash_size ,
2938 allowed range is 16 to 65536.
2940 .It Cm mask Ar mask-specifier
2941 Packets sent to a given pipe or queue by an
2943 rule can be further classified into multiple flows, each of which is then
2947 A flow identifier is constructed by masking the IP addresses,
2948 ports and protocol types as specified with the
2950 options in the configuration of the pipe or queue.
2951 For each different flow identifier, a new pipe or queue is created
2952 with the same parameters as the original object, and matching packets
2957 are used, each flow will get the same bandwidth as defined by the pipe,
2960 are used, each flow will share the parent's pipe bandwidth evenly
2961 with other flows generated by the same queue (note that other queues
2962 with different weights might be connected to the same pipe).
2964 Available mask specifiers are a combination of one or more of the following:
2966 .Cm dst-ip Ar mask ,
2967 .Cm dst-ip6 Ar mask ,
2968 .Cm src-ip Ar mask ,
2969 .Cm src-ip6 Ar mask ,
2970 .Cm dst-port Ar mask ,
2971 .Cm src-port Ar mask ,
2972 .Cm flow-id Ar mask ,
2977 where the latter means all bits in all fields are significant.
2980 When a packet is dropped by a
2982 queue or pipe, the error
2983 is normally reported to the caller routine in the kernel, in the
2984 same way as it happens when a device queue fills up.
2986 option reports the packet as successfully delivered, which can be
2987 needed for some experimental setups where you want to simulate
2988 loss or congestion at a remote router.
2990 .It Cm plr Ar packet-loss-rate
2993 .Ar packet-loss-rate
2994 is a floating-point number between 0 and 1, with 0 meaning no
2995 loss, 1 meaning 100% loss.
2996 The loss rate is internally represented on 31 bits.
2998 .It Cm queue Brq Ar slots | size Ns Cm Kbytes
3003 Default value is 50 slots, which
3004 is the typical queue size for Ethernet devices.
3005 Note that for slow speed links you should keep the queue
3006 size short or your traffic might be affected by a significant
3008 E.g., 50 max-sized Ethernet packets (1500 bytes) mean 600Kbit
3009 or 20s of queue on a 30Kbit/s pipe.
3010 Even worse effects can result if you get packets from an
3011 interface with a much larger MTU, e.g.\& the loopback interface
3012 with its 16KB packets.
3016 .Em net.inet.ip.dummynet.pipe_byte_limit
3018 .Em net.inet.ip.dummynet.pipe_slot_limit
3019 control the maximum lengths that can be specified.
3021 .It Cm red | gred Ar w_q Ns / Ns Ar min_th Ns / Ns Ar max_th Ns / Ns Ar max_p
3023 Make use of the RED (Random Early Detection) queue management algorithm.
3028 point numbers between 0 and 1 (inclusive), while
3032 are integer numbers specifying thresholds for queue management
3033 (thresholds are computed in bytes if the queue has been defined
3034 in bytes, in slots otherwise).
3035 The two parameters can also be of the same value if needed.
3038 also supports the gentle RED variant (gred) and ECN (Explicit Congestion
3039 Notification) as optional.
3042 variables can be used to control the RED behaviour:
3043 .Bl -tag -width indent
3044 .It Va net.inet.ip.dummynet.red_lookup_depth
3045 specifies the accuracy in computing the average queue
3046 when the link is idle (defaults to 256, must be greater than zero)
3047 .It Va net.inet.ip.dummynet.red_avg_pkt_size
3048 specifies the expected average packet size (defaults to 512, must be
3050 .It Va net.inet.ip.dummynet.red_max_pkt_size
3051 specifies the expected maximum packet size, only used when queue
3052 thresholds are in bytes (defaults to 1500, must be greater than zero).
3055 .It Cm codel Oo Cm target Ar time Oc Oo Cm interval Ar time Oc Oo Cm ecn |
3057 Make use of the CoDel (Controlled-Delay) queue management algorithm.
3059 is interpreted as milliseconds by default but seconds (s), milliseconds (ms) or
3060 microseconds (us) can be specified instead.
3061 CoDel drops or marks (ECN) packets
3062 depending on packet sojourn time in the queue.
3065 (5ms by default) is the minimum acceptable persistent queue delay that CoDel
3067 CoDel does not drop packets directly after packets sojourn time becomes
3074 (100ms default) before dropping.
3077 should be set to maximum RTT for all expected connections.
3079 enables (disabled by default) packet marking (instead of dropping) for
3080 ECN-enabled TCP flows when queue delay becomes high.
3082 Note that any token after
3084 is considered a parameter for CoDel.
3085 So, ensure all pipe/queue
3086 configuration options are written before
3093 .Va net.inet.ip.dummynet.codel.target
3095 .Va net.inet.ip.dummynet.codel.interval
3096 can be used to set CoDel default parameters.
3098 .It Cm pie Oo Cm target Ar time Oc Oo Cm tupdate Ar time Oc Oo
3099 .Cm alpha Ar n Oc Oo Cm beta Ar n Oc Oo Cm max_burst Ar time Oc Oo
3100 .Cm max_ecnth Ar n Oc Oo Cm ecn | Cm noecn Oc Oo Cm capdrop |
3101 .Cm nocapdrop Oc Oo Cm drand | Cm nodrand Oc Oo Cm onoff
3102 .Oc Oo Cm dre | Cm ts Oc
3103 Make use of the PIE (Proportional Integral controller Enhanced) queue management
3105 PIE drops or marks packets depending on a calculated drop probability during
3106 en-queue process, with the aim of achieving high throughput while keeping queue
3108 At regular time intervals of
3111 (15ms by default) a background process (re)calculates the probability based on queue delay
3115 (15ms by default) and queue delay trends.
3116 PIE approximates current queue
3117 delay by using a departure rate estimation method, or (optionally) by using a
3118 packet timestamp method similar to CoDel.
3120 is interpreted as milliseconds by default but seconds (s), milliseconds (ms) or
3121 microseconds (us) can be specified instead.
3122 The other PIE parameters and options are as follows:
3123 .Bl -tag -width indent
3126 is a floating point number between 0 and 7 which specifies the weight of queue
3127 delay deviations that is used in drop probability calculation.
3128 0.125 is the default.
3131 is a floating point number between 0 and 7 which specifies is the weight of queue
3132 delay trend that is used in drop probability calculation.
3133 1.25 is the default.
3134 .It Cm max_burst Ar time
3135 The maximum period of time that PIE does not drop/mark packets.
3137 default and 10s is the maximum value.
3138 .It Cm max_ecnth Ar n
3139 Even when ECN is enabled, PIE drops packets instead of marking them when drop
3140 probability becomes higher than ECN probability threshold
3142 , the default is 0.1 (i.e 10%) and 1 is the maximum value.
3144 enable or disable ECN marking for ECN-enabled TCP flows.
3145 Disabled by default.
3146 .It Cm capdrop | nocapdrop
3147 enable or disable cap drop adjustment.
3148 Cap drop adjustment is enabled by default.
3149 .It Cm drand | nodrand
3150 enable or disable drop probability de-randomisation.
3151 De-randomisation eliminates
3152 the problem of dropping packets too close or too far.
3153 De-randomisation is enabled by default.
3155 enable turning PIE on and off depending on queue load.
3156 If this option is enabled,
3157 PIE turns on when over 1/3 of queue becomes full.
3158 This option is disabled by
3161 Calculate queue delay using departure rate estimation
3169 Note that any token after
3171 is considered a parameter for PIE.
3172 So ensure all pipe/queue
3173 the configuration options are written before
3177 variables can be used to control the
3181 .Sx SYSCTL VARIABLES
3182 section for more details.
3185 When used with IPv6 data,
3187 currently has several limitations.
3188 Information necessary to route link-local packets to an
3189 interface is not available after processing by
3191 so those packets are dropped in the output path.
3192 Care should be taken to ensure that link-local packets are not passed to
3195 Here are some important points to consider when designing your
3199 Remember that you filter both packets going
3203 Most connections need packets going in both directions.
3205 Remember to test very carefully.
3206 It is a good idea to be near the console when doing this.
3207 If you cannot be near the console,
3208 use an auto-recovery script such as the one in
3209 .Pa /usr/share/examples/ipfw/change_rules.sh .
3211 Do not forget the loopback interface.
3216 There are circumstances where fragmented datagrams are unconditionally
3218 TCP packets are dropped if they do not contain at least 20 bytes of
3219 TCP header, UDP packets are dropped if they do not contain a full 8
3220 byte UDP header, and ICMP packets are dropped if they do not contain
3221 4 bytes of ICMP header, enough to specify the ICMP type, code, and
3223 These packets are simply logged as
3225 since there may not be enough good data in the packet to produce a
3226 meaningful log entry.
3228 Another type of packet is unconditionally dropped, a TCP packet with a
3229 fragment offset of one.
3230 This is a valid packet, but it only has one use, to try
3231 to circumvent firewalls.
3232 When logging is enabled, these packets are
3233 reported as being dropped by rule -1.
3235 If you are logged in over a network, loading the
3239 is probably not as straightforward as you would think.
3240 The following command line is recommended:
3241 .Bd -literal -offset indent
3243 ipfw add 32000 allow ip from any to any
3246 Along the same lines, doing an
3247 .Bd -literal -offset indent
3251 in similar surroundings is also a bad idea.
3255 filter list may not be modified if the system security level
3256 is set to 3 or higher
3259 for information on system security levels).
3261 .Sh PACKET DIVERSION
3264 socket bound to the specified port will receive all packets
3265 diverted to that port.
3266 If no socket is bound to the destination port, or if the divert module is
3267 not loaded, or if the kernel was not compiled with divert socket support,
3268 the packets are dropped.
3269 .Sh NETWORK ADDRESS TRANSLATION (NAT)
3271 support in-kernel NAT using the kernel version of
3275 should be loaded or kernel should have
3276 .Cm options IPFIREWALL_NAT
3279 The nat configuration command is the following:
3280 .Bd -ragged -offset indent
3285 .Ar nat-configuration
3289 The following parameters can be configured:
3290 .Bl -tag -width indent
3291 .It Cm ip Ar ip_address
3292 Define an ip address to use for aliasing.
3294 Use ip address of NIC for aliasing, dynamically changing
3295 it if NIC's ip address changes.
3297 Enable logging on this nat instance.
3299 Deny any incoming connection from outside world.
3301 Try to leave the alias port numbers unchanged from
3302 the actual local port numbers.
3304 Traffic on the local network not originating from a RFC 1918
3305 unregistered address spaces will be ignored.
3307 Like unreg_only, but includes the RFC 6598 (Carrier Grade NAT)
3310 Reset table of the packet aliasing engine on address change.
3312 Reverse the way libalias handles aliasing.
3314 Obey transparent proxy rules only, packet aliasing is not performed.
3316 Skip instance in case of global state lookup (see below).
3317 .It Cm port_range Ar lower-upper
3318 Set the aliasing ports between the ranges given. Upper port has to be greater
3322 Some special values can be supplied instead of
3324 in nat rule actions:
3325 .Bl -tag -width indent
3327 Looks up translation state in all configured nat instances.
3328 If an entry is found, packet is aliased according to that entry.
3329 If no entry was found in any of the instances, packet is passed unchanged,
3330 and no new entry will be created.
3332 .Sx MULTIPLE INSTANCES
3335 for more information.
3337 Uses argument supplied in lookup table.
3340 section below for more information on lookup tables.
3343 To let the packet continue after being (de)aliased, set the sysctl variable
3344 .Va net.inet.ip.fw.one_pass
3346 For more information about aliasing modes, refer to
3350 for some examples of nat usage.
3351 .Ss REDIRECT AND LSNAT SUPPORT IN IPFW
3352 Redirect and LSNAT support follow closely the syntax used in
3356 for some examples on how to do redirect and lsnat.
3357 .Ss SCTP NAT SUPPORT
3358 SCTP nat can be configured in a similar manner to TCP through the
3361 The main difference is that
3363 does not do port translation.
3364 Since the local and global side ports will be the same,
3365 there is no need to specify both.
3366 Ports are redirected as follows:
3367 .Bd -ragged -offset indent
3373 .Cm redirect_port sctp
3374 .Ar ip_address [,addr_list] {[port | port-port] [,ports]}
3380 configuration can be done in real-time through the
3383 All may be changed dynamically, though the hash_table size will only
3388 .Sx SYSCTL VARIABLES
3390 .Sh IPv6/IPv4 NETWORK ADDRESS AND PROTOCOL TRANSLATION
3391 .Ss Stateful translation
3393 supports in-kernel IPv6/IPv4 network address and protocol translation.
3394 Stateful NAT64 translation allows IPv6-only clients to contact IPv4 servers
3395 using unicast TCP, UDP or ICMP protocols.
3396 One or more IPv4 addresses assigned to a stateful NAT64 translator are shared
3397 among several IPv6-only clients.
3398 When stateful NAT64 is used in conjunction with DNS64, no changes are usually
3399 required in the IPv6 client or the IPv4 server.
3402 should be loaded or kernel should have
3403 .Cm options IPFIREWALL_NAT64
3404 to be able use stateful NAT64 translator.
3406 Stateful NAT64 uses a bunch of memory for several types of objects.
3407 When IPv6 client initiates connection, NAT64 translator creates a host entry
3408 in the states table.
3409 Each host entry uses preallocated IPv4 alias entry.
3410 Each alias entry has a number of ports group entries allocated on demand.
3411 Ports group entries contains connection state entries.
3412 There are several options to control limits and lifetime for these objects.
3414 NAT64 translator follows RFC7915 when does ICMPv6/ICMP translation,
3415 unsupported message types will be silently dropped.
3416 IPv6 needs several ICMPv6 message types to be explicitly allowed for correct
3418 Make sure that ND6 neighbor solicitation (ICMPv6 type 135) and neighbor
3419 advertisement (ICMPv6 type 136) messages will not be handled by translation
3422 After translation NAT64 translator by default sends packets through
3423 corresponding netisr queue.
3424 Thus translator host should be configured as IPv4 and IPv6 router.
3425 Also this means, that a packet is handled by firewall twice.
3426 First time an original packet is handled and consumed by translator,
3427 and then it is handled again as translated packet.
3428 This behavior can be changed by sysctl variable
3429 .Va net.inet.ip.fw.nat64_direct_output .
3430 Also translated packet can be tagged using
3432 rule action, and then matched by
3434 opcode to avoid loops and extra overhead.
3436 The stateful NAT64 configuration command is the following:
3437 .Bd -ragged -offset indent
3446 The following parameters can be configured:
3447 .Bl -tag -width indent
3448 .It Cm prefix4 Ar ipv4_prefix/plen
3449 The IPv4 prefix with mask defines the pool of IPv4 addresses used as
3450 source address after translation.
3451 Stateful NAT64 module translates IPv6 source address of client to one
3452 IPv4 address from this pool.
3453 Note that incoming IPv4 packets that don't have corresponding state entry
3454 in the states table will be dropped by translator.
3455 Make sure that translation rules handle packets, destined to configured prefix.
3456 .It Cm prefix6 Ar ipv6_prefix/length
3457 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3458 to represent IPv4 addresses.
3459 This IPv6 prefix should be configured in DNS64.
3460 The translator implementation follows RFC6052, that restricts the length of
3461 prefixes to one of following: 32, 40, 48, 56, 64, or 96.
3462 The Well-Known IPv6 Prefix 64:ff9b:: must be 96 bits long.
3465 prefix can be used to handle several IPv6 prefixes with one NAT64 instance.
3466 The NAT64 instance will determine a destination IPv4 address from prefix
3468 .It Cm states_chunks Ar number
3469 The number of states chunks in single ports group.
3470 Each ports group by default can keep 64 state entries in single chunk.
3471 The above value affects the maximum number of states that can be associated with single IPv4 alias address and port.
3472 The value must be power of 2, and up to 128.
3473 .It Cm host_del_age Ar seconds
3474 The number of seconds until the host entry for a IPv6 client will be deleted
3475 and all its resources will be released due to inactivity.
3478 .It Cm pg_del_age Ar seconds
3479 The number of seconds until a ports group with unused state entries will
3483 .It Cm tcp_syn_age Ar seconds
3484 The number of seconds while a state entry for TCP connection with only SYN
3486 If TCP connection establishing will not be finished,
3487 state entry will be deleted.
3490 .It Cm tcp_est_age Ar seconds
3491 The number of seconds while a state entry for established TCP connection
3495 .It Cm tcp_close_age Ar seconds
3496 The number of seconds while a state entry for closed TCP connection
3498 Keeping state entries for closed connections is needed, because IPv4 servers
3499 typically keep closed connections in a TIME_WAIT state for a several minutes.
3500 Since translator's IPv4 addresses are shared among all IPv6 clients,
3501 new connections from the same addresses and ports may be rejected by server,
3502 because these connections are still in a TIME_WAIT state.
3503 Keeping them in translator's state table protects from such rejects.
3506 .It Cm udp_age Ar seconds
3507 The number of seconds while translator keeps state entry in a waiting for
3508 reply to the sent UDP datagram.
3511 .It Cm icmp_age Ar seconds
3512 The number of seconds while translator keeps state entry in a waiting for
3513 reply to the sent ICMP message.
3517 Turn on logging of all handled packets via BPF through
3521 is a pseudo interface and can be created after a boot manually with
3524 Note that it has different purpose than
3527 Translators sends to BPF an additional information with each packet.
3530 you are able to see each handled packet before and after translation.
3532 Turn off logging of all handled packets via BPF.
3533 .It Cm allow_private
3534 Turn on processing private IPv4 addresses.
3535 By default IPv6 packets with destinations mapped to private address ranges
3536 defined by RFC1918 are not processed.
3537 .It Cm -allow_private
3538 Turn off private address handling in
3543 To inspect a states table of stateful NAT64 the following command can be used:
3544 .Bd -ragged -offset indent
3552 Stateless NAT64 translator doesn't use a states table for translation
3553 and converts IPv4 addresses to IPv6 and vice versa solely based on the
3554 mappings taken from configured lookup tables.
3555 Since a states table doesn't used by stateless translator,
3556 it can be configured to pass IPv4 clients to IPv6-only servers.
3558 The stateless NAT64 configuration command is the following:
3559 .Bd -ragged -offset indent
3568 The following parameters can be configured:
3569 .Bl -tag -width indent
3570 .It Cm prefix6 Ar ipv6_prefix/length
3571 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3572 to represent IPv4 addresses.
3573 This IPv6 prefix should be configured in DNS64.
3574 .It Cm table4 Ar table46
3577 contains mapping how IPv4 addresses should be translated to IPv6 addresses.
3578 .It Cm table6 Ar table64
3581 contains mapping how IPv6 addresses should be translated to IPv4 addresses.
3583 Turn on logging of all handled packets via BPF through
3587 Turn off logging of all handled packets via BPF.
3588 .It Cm allow_private
3589 Turn on processing private IPv4 addresses.
3590 By default IPv6 packets with destinations mapped to private address ranges
3591 defined by RFC1918 are not processed.
3592 .It Cm -allow_private
3593 Turn off private address handling in
3598 Note that the behavior of stateless translator with respect to not matched
3599 packets differs from stateful translator.
3600 If corresponding addresses was not found in the lookup tables, the packet
3601 will not be dropped and the search continues.
3602 .Ss XLAT464 CLAT translation
3603 XLAT464 CLAT NAT64 translator implements client-side stateless translation as
3604 defined in RFC6877 and is very similar to statless NAT64 translator
3606 Instead of lookup tables it uses one-to-one mapping between IPv4 and IPv6
3607 addresses using configured prefixes.
3608 This mode can be used as a replacement of DNS64 service for applications
3609 that are not using it (e.g. VoIP) allowing them to access IPv4-only Internet
3610 over IPv6-only networks with help of remote NAT64 translator.
3612 The CLAT NAT64 configuration command is the following:
3613 .Bd -ragged -offset indent
3622 The following parameters can be configured:
3623 .Bl -tag -width indent
3624 .It Cm clat_prefix Ar ipv6_prefix/length
3625 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3626 to represent source IPv4 addresses.
3627 .It Cm plat_prefix Ar ipv6_prefix/length
3628 The IPv6 prefix defines IPv4-embedded IPv6 addresses used by translator
3629 to represent destination IPv4 addresses.
3630 This IPv6 prefix should be configured on a remote NAT64 translator.
3632 Turn on logging of all handled packets via BPF through
3636 Turn off logging of all handled packets via BPF.
3637 .It Cm allow_private
3638 Turn on processing private IPv4 addresses.
3641 instance will not process IPv4 packets with destination address from private
3642 ranges as defined in RFC1918.
3643 .It Cm -allow_private
3644 Turn off private address handling in
3649 Note that the behavior of CLAT translator with respect to not matched
3650 packets differs from stateful translator.
3651 If corresponding addresses were not matched against prefixes configured,
3652 the packet will not be dropped and the search continues.
3653 .Sh IPv6-to-IPv6 NETWORK PREFIX TRANSLATION (NPTv6)
3655 supports in-kernel IPv6-to-IPv6 network prefix translation as described
3659 should be loaded or kernel should has
3660 .Cm options IPFIREWALL_NPTV6
3661 to be able use NPTv6 translator.
3663 The NPTv6 configuration command is the following:
3664 .Bd -ragged -offset indent
3673 The following parameters can be configured:
3674 .Bl -tag -width indent
3675 .It Cm int_prefix Ar ipv6_prefix
3676 IPv6 prefix used in internal network.
3677 NPTv6 module translates source address when it matches this prefix.
3678 .It Cm ext_prefix Ar ipv6_prefix
3679 IPv6 prefix used in external network.
3680 NPTv6 module translates destination address when it matches this prefix.
3681 .It Cm ext_if Ar nic
3682 The NPTv6 module will use first global IPv6 address from interface
3685 It can be useful when IPv6 prefix of external network is dynamically obtained.
3689 options are mutually exclusive.
3690 .It Cm prefixlen Ar length
3691 The length of specified IPv6 prefixes.
3692 It must be in range from 8 to 64.
3695 Note that the prefix translation rules are silently ignored when IPv6 packet
3696 forwarding is disabled.
3697 To enable the packet forwarding, set the sysctl variable
3698 .Va net.inet6.ip6.forwarding
3701 To let the packet continue after being translated, set the sysctl variable
3702 .Va net.inet.ip.fw.one_pass
3705 Tunables can be set in
3711 before ipfw module gets loaded.
3712 .Bl -tag -width indent
3713 .It Va net.inet.ip.fw.default_to_accept : No 0
3714 Defines ipfw last rule behavior.
3715 This value overrides
3716 .Cd "options IPFW_DEFAULT_TO_(ACCEPT|DENY)"
3717 from kernel configuration file.
3718 .It Va net.inet.ip.fw.tables_max : No 128
3719 Defines number of tables available in ipfw.
3720 Number cannot exceed 65534.
3722 .Sh SYSCTL VARIABLES
3725 variables controls the behaviour of the firewall and
3727 .Pq Nm dummynet , bridge , sctp nat .
3728 These are shown below together with their default value
3729 (but always check with the
3731 command what value is actually in use) and meaning:
3732 .Bl -tag -width indent
3733 .It Va net.inet.ip.alias.sctp.accept_global_ootb_addip : No 0
3736 responds to receipt of global OOTB ASCONF-AddIP:
3737 .Bl -tag -width indent
3739 No response (unless a partially matching association exists -
3740 ports and vtags match but global address does not)
3743 will accept and process all OOTB global AddIP messages.
3746 Option 1 should never be selected as this forms a security risk.
3748 establish multiple fake associations by sending AddIP messages.
3749 .It Va net.inet.ip.alias.sctp.chunk_proc_limit : No 5
3750 Defines the maximum number of chunks in an SCTP packet that will be
3752 packet that matches an existing association.
3753 This value is enforced to be greater or equal than
3754 .Cm net.inet.ip.alias.sctp.initialising_chunk_proc_limit .
3756 a DoS risk yet setting too low a value may result in
3757 important control chunks in
3758 the packet not being located and parsed.
3759 .It Va net.inet.ip.alias.sctp.error_on_ootb : No 1
3762 responds to any Out-of-the-Blue (OOTB) packets with ErrorM packets.
3763 An OOTB packet is a packet that arrives with no existing association
3766 and is not an INIT or ASCONF-AddIP packet:
3767 .Bl -tag -width indent
3769 ErrorM is never sent in response to OOTB packets.
3771 ErrorM is only sent to OOTB packets received on the local side.
3773 ErrorM is sent to the local side and on the global side ONLY if there is a
3774 partial match (ports and vtags match but the source global IP does not).
3775 This value is only useful if the
3777 is tracking global IP addresses.
3779 ErrorM is sent in response to all OOTB packets on both
3780 the local and global side
3784 At the moment the default is 0, since the ErrorM packet is not yet
3785 supported by most SCTP stacks.
3786 When it is supported, and if not tracking
3787 global addresses, we recommend setting this value to 1 to allow
3788 multi-homed local hosts to function with the
3790 To track global addresses, we recommend setting this value to 2 to
3791 allow global hosts to be informed when they need to (re)send an
3793 Value 3 should never be chosen (except for debugging) as the
3795 will respond to all OOTB global packets (a DoS risk).
3796 .It Va net.inet.ip.alias.sctp.hashtable_size : No 2003
3797 Size of hash tables used for
3799 lookups (100 < prime_number > 1000001).
3802 size for any future created
3804 instance and therefore must be set prior to creating a
3807 The table sizes may be changed to suit specific needs.
3808 If there will be few
3809 concurrent associations, and memory is scarce, you may make these smaller.
3810 If there will be many thousands (or millions) of concurrent associations, you
3811 should make these larger.
3812 A prime number is best for the table size.
3814 update function will adjust your input value to the next highest prime number.
3815 .It Va net.inet.ip.alias.sctp.holddown_time : No 0
3816 Hold association in table for this many seconds after receiving a
3818 This allows endpoints to correct shutdown gracefully if a
3819 shutdown_complete is lost and retransmissions are required.
3820 .It Va net.inet.ip.alias.sctp.init_timer : No 15
3821 Timeout value while waiting for (INIT-ACK|AddIP-ACK).
3822 This value cannot be 0.
3823 .It Va net.inet.ip.alias.sctp.initialising_chunk_proc_limit : No 2
3824 Defines the maximum number of chunks in an SCTP packet that will be parsed when
3825 no existing association exists that matches that packet.
3827 will only be an INIT or ASCONF-AddIP packet.
3828 A higher value may become a DoS
3829 risk as malformed packets can consume processing resources.
3830 .It Va net.inet.ip.alias.sctp.param_proc_limit : No 25
3831 Defines the maximum number of parameters within a chunk that will be
3834 As for other similar sysctl variables, larger values pose a DoS risk.
3835 .It Va net.inet.ip.alias.sctp.log_level : No 0
3836 Level of detail in the system log messages (0 \- minimal, 1 \- event,
3837 2 \- info, 3 \- detail, 4 \- debug, 5 \- max debug).
3839 option in high loss environments.
3840 .It Va net.inet.ip.alias.sctp.shutdown_time : No 15
3841 Timeout value while waiting for SHUTDOWN-COMPLETE.
3842 This value cannot be 0.
3843 .It Va net.inet.ip.alias.sctp.track_global_addresses : No 0
3844 Enables/disables global IP address tracking within the
3847 upper limit on the number of addresses tracked for each association:
3848 .Bl -tag -width indent
3850 Global tracking is disabled
3852 Enables tracking, the maximum number of addresses tracked for each
3853 association is limited to this value
3856 This variable is fully dynamic, the new value will be adopted for all newly
3857 arriving associations, existing associations are treated
3858 as they were previously.
3859 Global tracking will decrease the number of collisions within the
3862 of increased processing load, memory usage, complexity, and possible
3865 problems in complex networks with multiple
3867 We recommend not tracking
3868 global IP addresses, this will still result in a fully functional
3870 .It Va net.inet.ip.alias.sctp.up_timer : No 300
3871 Timeout value to keep an association up with no traffic.
3872 This value cannot be 0.
3873 .It Va net.inet.ip.dummynet.codel.interval : No 100000
3876 AQM interval in microseconds.
3877 The value must be in the range 1..5000000.
3878 .It Va net.inet.ip.dummynet.codel.target : No 5000
3881 AQM target delay time in microseconds (the minimum acceptable persistent queue
3883 The value must be in the range 1..5000000.
3884 .It Va net.inet.ip.dummynet.expire : No 1
3885 Lazily delete dynamic pipes/queue once they have no pending traffic.
3886 You can disable this by setting the variable to 0, in which case
3887 the pipes/queues will only be deleted when the threshold is reached.
3888 .It Va net.inet.ip.dummynet.fqcodel.flows : No 1024
3889 Defines the default total number of flow queues (sub-queues) that
3891 creates and manages.
3892 The value must be in the range 1..65536.
3893 .It Va net.inet.ip.dummynet.fqcodel.interval : No 100000
3896 scheduler/AQM interval in microseconds.
3897 The value must be in the range 1..5000000.
3898 .It Va net.inet.ip.dummynet.fqcodel.limit : No 10240
3899 The default hard size limit (in unit of packet) of all queues managed by an
3903 The value must be in the range 1..20480.
3904 .It Va net.inet.ip.dummynet.fqcodel.quantum : No 1514
3905 The default quantum (credit) of the
3908 The value must be in the range 1..9000.
3909 .It Va net.inet.ip.dummynet.fqcodel.target : No 5000
3912 scheduler/AQM target delay time in microseconds (the minimum acceptable
3913 persistent queue delay).
3914 The value must be in the range 1..5000000.
3915 .It Va net.inet.ip.dummynet.fqpie.alpha : No 125
3918 parameter (scaled by 1000) for
3921 The value must be in the range 1..7000.
3922 .It Va net.inet.ip.dummynet.fqpie.beta : No 1250
3925 parameter (scaled by 1000) for
3928 The value must be in the range 1..7000.
3929 .It Va net.inet.ip.dummynet.fqpie.flows : No 1024
3930 Defines the default total number of flow queues (sub-queues) that
3932 creates and manages.
3933 The value must be in the range 1..65536.
3934 .It Va net.inet.ip.dummynet.fqpie.limit : No 10240
3935 The default hard size limit (in unit of packet) of all queues managed by an
3939 The value must be in the range 1..20480.
3940 .It Va net.inet.ip.dummynet.fqpie.max_burst : No 150000
3941 The default maximum period of microseconds that
3943 scheduler/AQM does not drop/mark packets.
3944 The value must be in the range 1..10000000.
3945 .It Va net.inet.ip.dummynet.fqpie.max_ecnth : No 99
3946 The default maximum ECN probability threshold (scaled by 1000) for
3949 The value must be in the range 1..7000.
3950 .It Va net.inet.ip.dummynet.fqpie.quantum : No 1514
3951 The default quantum (credit) of the
3954 The value must be in the range 1..9000.
3955 .It Va net.inet.ip.dummynet.fqpie.target : No 15000
3960 in unit of microsecond.
3961 The value must be in the range 1..5000000.
3962 .It Va net.inet.ip.dummynet.fqpie.tupdate : No 15000
3967 in unit of microsecond.
3968 The value must be in the range 1..5000000.
3969 .It Va net.inet.ip.dummynet.hash_size : No 64
3970 Default size of the hash table used for dynamic pipes/queues.
3971 This value is used when no
3973 option is specified when configuring a pipe/queue.
3974 .It Va net.inet.ip.dummynet.io_fast : No 0
3975 If set to a non-zero value,
3980 operation (see above) is enabled.
3981 .It Va net.inet.ip.dummynet.io_pkt
3982 Number of packets passed to
3984 .It Va net.inet.ip.dummynet.io_pkt_drop
3985 Number of packets dropped by
3987 .It Va net.inet.ip.dummynet.io_pkt_fast
3988 Number of packets bypassed by the
3991 .It Va net.inet.ip.dummynet.max_chain_len : No 16
3992 Target value for the maximum number of pipes/queues in a hash bucket.
3994 .Cm max_chain_len*hash_size
3995 is used to determine the threshold over which empty pipes/queues
3996 will be expired even when
3997 .Cm net.inet.ip.dummynet.expire=0 .
3998 .It Va net.inet.ip.dummynet.red_lookup_depth : No 256
3999 .It Va net.inet.ip.dummynet.red_avg_pkt_size : No 512
4000 .It Va net.inet.ip.dummynet.red_max_pkt_size : No 1500
4001 Parameters used in the computations of the drop probability
4002 for the RED algorithm.
4003 .It Va net.inet.ip.dummynet.pie.alpha : No 125
4006 parameter (scaled by 1000) for
4009 The value must be in the range 1..7000.
4010 .It Va net.inet.ip.dummynet.pie.beta : No 1250
4013 parameter (scaled by 1000) for
4016 The value must be in the range 1..7000.
4017 .It Va net.inet.ip.dummynet.pie.max_burst : No 150000
4018 The default maximum period of microseconds that
4020 AQM does not drop/mark packets.
4021 The value must be in the range 1..10000000.
4022 .It Va net.inet.ip.dummynet.pie.max_ecnth : No 99
4023 The default maximum ECN probability threshold (scaled by 1000) for
4026 The value must be in the range 1..7000.
4027 .It Va net.inet.ip.dummynet.pie.target : No 15000
4032 AQM in unit of microsecond.
4033 The value must be in the range 1..5000000.
4034 .It Va net.inet.ip.dummynet.pie.tupdate : No 15000
4039 AQM in unit of microsecond.
4040 The value must be in the range 1..5000000.
4041 .It Va net.inet.ip.dummynet.pipe_byte_limit : No 1048576
4042 .It Va net.inet.ip.dummynet.pipe_slot_limit : No 100
4043 The maximum queue size that can be specified in bytes or packets.
4044 These limits prevent accidental exhaustion of resources such as mbufs.
4045 If you raise these limits,
4046 you should make sure the system is configured so that sufficient resources
4048 .It Va net.inet.ip.fw.autoinc_step : No 100
4049 Delta between rule numbers when auto-generating them.
4050 The value must be in the range 1..1000.
4051 .It Va net.inet.ip.fw.curr_dyn_buckets : Va net.inet.ip.fw.dyn_buckets
4052 The current number of buckets in the hash table for dynamic rules
4054 .It Va net.inet.ip.fw.debug : No 1
4055 Controls debugging messages produced by
4057 .It Va net.inet.ip.fw.default_rule : No 65535
4058 The default rule number (read-only).
4060 .Nm , the default rule is the last one, so its number
4061 can also serve as the highest number allowed for a rule.
4062 .It Va net.inet.ip.fw.dyn_buckets : No 256
4063 The number of buckets in the hash table for dynamic rules.
4064 Must be a power of 2, up to 65536.
4065 It only takes effect when all dynamic rules have expired, so you
4066 are advised to use a
4068 command to make sure that the hash table is resized.
4069 .It Va net.inet.ip.fw.dyn_count : No 3
4070 Current number of dynamic rules
4072 .It Va net.inet.ip.fw.dyn_keepalive : No 1
4073 Enables generation of keepalive packets for
4075 rules on TCP sessions.
4076 A keepalive is generated to both
4077 sides of the connection every 5 seconds for the last 20
4078 seconds of the lifetime of the rule.
4079 .It Va net.inet.ip.fw.dyn_max : No 8192
4080 Maximum number of dynamic rules.
4081 When you hit this limit, no more dynamic rules can be
4082 installed until old ones expire.
4083 .It Va net.inet.ip.fw.dyn_ack_lifetime : No 300
4084 .It Va net.inet.ip.fw.dyn_syn_lifetime : No 20
4085 .It Va net.inet.ip.fw.dyn_fin_lifetime : No 1
4086 .It Va net.inet.ip.fw.dyn_rst_lifetime : No 1
4087 .It Va net.inet.ip.fw.dyn_udp_lifetime : No 5
4088 .It Va net.inet.ip.fw.dyn_short_lifetime : No 30
4089 These variables control the lifetime, in seconds, of dynamic
4091 Upon the initial SYN exchange the lifetime is kept short,
4092 then increased after both SYN have been seen, then decreased
4093 again during the final FIN exchange or when a RST is received.
4095 .Em dyn_fin_lifetime
4097 .Em dyn_rst_lifetime
4098 must be strictly lower than 5 seconds, the period of
4099 repetition of keepalives.
4100 The firewall enforces that.
4101 .It Va net.inet.ip.fw.dyn_keep_states : No 0
4102 Keep dynamic states on rule/set deletion.
4103 States are relinked to default rule (65535).
4104 This can be handly for ruleset reload.
4105 Turned off by default.
4106 .It Va net.inet.ip.fw.enable : No 1
4107 Enables the firewall.
4108 Setting this variable to 0 lets you run your machine without
4109 firewall even if compiled in.
4110 .It Va net.inet6.ip6.fw.enable : No 1
4111 provides the same functionality as above for the IPv6 case.
4112 .It Va net.inet.ip.fw.one_pass : No 1
4113 When set, the packet exiting from the
4117 node is not passed though the firewall again.
4118 Otherwise, after an action, the packet is
4119 reinjected into the firewall at the next rule.
4120 .It Va net.inet.ip.fw.tables_max : No 128
4121 Maximum number of tables.
4122 .It Va net.inet.ip.fw.verbose : No 1
4123 Enables verbose messages.
4124 .It Va net.inet.ip.fw.verbose_limit : No 0
4125 Limits the number of messages produced by a verbose firewall.
4126 .It Va net.inet6.ip6.fw.deny_unknown_exthdrs : No 1
4127 If enabled packets with unknown IPv6 Extension Headers will be denied.
4128 .It Va net.link.ether.ipfw : No 0
4129 Controls whether layer2 packets are passed to
4132 .It Va net.link.bridge.ipfw : No 0
4133 Controls whether bridged packets are passed to
4136 .It Va net.inet.ip.fw.nat64_debug : No 0
4137 Controls debugging messages produced by
4140 .It Va net.inet.ip.fw.nat64_direct_output : No 0
4141 Controls the output method used by
4144 .Bl -tag -width indent
4146 A packet is handled by
4149 First time an original packet is handled by
4154 Then translated packet is queued via netisr to input processing again.
4156 A packet is handled by
4158 only once, and after translation it will be pushed directly to outgoing
4162 .Sh INTERNAL DIAGNOSTICS
4163 There are some commands that may be useful to understand current state
4164 of certain subsystems inside kernel module.
4165 These commands provide debugging output which may change without notice.
4167 Currently the following commands are available as
4170 .Bl -tag -width indent
4172 Lists all interface which are currently tracked by
4174 with their in-kernel status.
4176 List all table lookup algorithms currently available.
4179 There are far too many possible uses of
4181 so this Section will only give a small set of examples.
4182 .Ss BASIC PACKET FILTERING
4183 This command adds an entry which denies all tcp packets from
4184 .Em cracker.evil.org
4185 to the telnet port of
4187 from being forwarded by the host:
4189 .Dl "ipfw add deny tcp from cracker.evil.org to wolf.tambov.su telnet"
4191 This one disallows any connection from the entire cracker's
4194 .Dl "ipfw add deny ip from 123.45.67.0/24 to my.host.org"
4196 A first and efficient way to limit access (not using dynamic rules)
4197 is the use of the following rules:
4199 .Dl "ipfw add allow tcp from any to any established"
4200 .Dl "ipfw add allow tcp from net1 portlist1 to net2 portlist2 setup"
4201 .Dl "ipfw add allow tcp from net3 portlist3 to net3 portlist3 setup"
4203 .Dl "ipfw add deny tcp from any to any"
4205 The first rule will be a quick match for normal TCP packets,
4206 but it will not match the initial SYN packet, which will be
4209 rules only for selected source/destination pairs.
4210 All other SYN packets will be rejected by the final
4214 If you administer one or more subnets, you can take advantage
4215 of the address sets and or-blocks and write extremely
4216 compact rulesets which selectively enable services to blocks
4217 of clients, as below:
4219 .Dl "goodguys=\*q{ 10.1.2.0/24{20,35,66,18} or 10.2.3.0/28{6,3,11} }\*q"
4220 .Dl "badguys=\*q10.1.2.0/24{8,38,60}\*q"
4222 .Dl "ipfw add allow ip from ${goodguys} to any"
4223 .Dl "ipfw add deny ip from ${badguys} to any"
4224 .Dl "... normal policies ..."
4228 option could be used to do automated anti-spoofing by adding the
4229 following to the top of a ruleset:
4231 .Dl "ipfw add deny ip from any to any not verrevpath in"
4233 This rule drops all incoming packets that appear to be coming to the
4234 system on the wrong interface.
4235 For example, a packet with a source
4236 address belonging to a host on a protected internal network would be
4237 dropped if it tried to enter the system from an external interface.
4241 option could be used to do similar but more restricted anti-spoofing
4242 by adding the following to the top of a ruleset:
4244 .Dl "ipfw add deny ip from any to any not antispoof in"
4246 This rule drops all incoming packets that appear to be coming from another
4247 directly connected system but on the wrong interface.
4248 For example, a packet with a source address of
4249 .Li 192.168.0.0/24 ,
4258 option could be used to (re)mark user traffic,
4259 by adding the following to the appropriate place in ruleset:
4261 .Dl "ipfw add setdscp be ip from any to any dscp af11,af21"
4262 .Ss SELECTIVE MIRRORING
4263 If your network has network traffic analyzer
4264 connected to your host directly via dedicated interface
4265 or remotely via RSPAN vlan, you can selectively mirror
4266 some Ethernet layer2 frames to the analyzer.
4268 First, make sure your firewall is already configured and runs.
4269 Then, enable layer2 processing if not already enabled:
4271 .Dl "sysctl net.link.ether.ipfw=1"
4273 Next, load needed additional kernel modules:
4275 .Dl "kldload ng_ether ng_ipfw"
4277 Optionally, make system load these modules automatically
4280 .Dl sysrc kld_list+="ng_ether ng_ipfw"
4284 kernel module to transmit mirrored copies of layer2 frames
4285 out via vlan900 interface:
4287 .Dl "ngctl connect ipfw: vlan900: 1 lower"
4289 Think of "1" here as of "mirroring instance index" and vlan900 is its
4291 You can have arbitrary number of instances.
4296 At last, actually start mirroring of selected frames using "instance 1".
4297 For frames incoming from em0 interface:
4299 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 in recv em0"
4301 For frames outgoing to em0 interface:
4303 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 out xmit em0"
4305 For both incoming and outgoing frames while flowing through em0:
4307 .Dl "ipfw add ngtee 1 ip from any to 192.168.0.1 layer2 via em0"
4309 Make sure you do not perform mirroring for already duplicated frames
4310 or kernel may hang as there is no safety net.
4312 In order to protect a site from flood attacks involving fake
4313 TCP packets, it is safer to use dynamic rules:
4315 .Dl "ipfw add check-state"
4316 .Dl "ipfw add deny tcp from any to any established"
4317 .Dl "ipfw add allow tcp from my-net to any setup keep-state"
4319 This will let the firewall install dynamic rules only for
4320 those connection which start with a regular SYN packet coming
4321 from the inside of our network.
4322 Dynamic rules are checked when encountering the first
4331 rule should usually be placed near the beginning of the
4332 ruleset to minimize the amount of work scanning the ruleset.
4333 Your mileage may vary.
4335 For more complex scenarios with dynamic rules
4339 can be used to precisely control creation and checking of dynamic rules.
4340 Example of usage of these options are provided in
4341 .Sx NETWORK ADDRESS TRANSLATION (NAT)
4344 To limit the number of connections a user can open
4345 you can use the following type of rules:
4347 .Dl "ipfw add allow tcp from my-net/24 to any setup limit src-addr 10"
4348 .Dl "ipfw add allow tcp from any to me setup limit src-addr 4"
4350 The former (assuming it runs on a gateway) will allow each host
4351 on a /24 network to open at most 10 TCP connections.
4352 The latter can be placed on a server to make sure that a single
4353 client does not use more than 4 simultaneous connections.
4356 stateful rules can be subject to denial-of-service attacks
4357 by a SYN-flood which opens a huge number of dynamic rules.
4358 The effects of such attacks can be partially limited by
4361 variables which control the operation of the firewall.
4363 Here is a good usage of the
4365 command to see accounting records and timestamp information:
4369 or in short form without timestamps:
4373 which is equivalent to:
4377 Next rule diverts all incoming packets from 192.168.2.0/24
4378 to divert port 5000:
4380 .Dl ipfw divert 5000 ip from 192.168.2.0/24 to any in
4382 The following rules show some of the applications of
4386 for simulations and the like.
4388 This rule drops random incoming packets with a probability
4391 .Dl "ipfw add prob 0.05 deny ip from any to any in"
4393 A similar effect can be achieved making use of
4397 .Dl "dnctl add pipe 10 ip from any to any"
4398 .Dl "dnctl pipe 10 config plr 0.05"
4400 We can use pipes to artificially limit bandwidth, e.g.\& on a
4401 machine acting as a router, if we want to limit traffic from
4402 local clients on 192.168.2.0/24 we do:
4404 .Dl "ipfw add pipe 1 ip from 192.168.2.0/24 to any out"
4405 .Dl "dnctl pipe 1 config bw 300Kbit/s queue 50KBytes"
4407 note that we use the
4409 modifier so that the rule is not used twice.
4410 Remember in fact that
4412 rules are checked both on incoming and outgoing packets.
4414 Should we want to simulate a bidirectional link with bandwidth
4415 limitations, the correct way is the following:
4417 .Dl "ipfw add pipe 1 ip from any to any out"
4418 .Dl "ipfw add pipe 2 ip from any to any in"
4419 .Dl "dnctl pipe 1 config bw 64Kbit/s queue 10Kbytes"
4420 .Dl "dnctl pipe 2 config bw 64Kbit/s queue 10Kbytes"
4422 The above can be very useful, e.g.\& if you want to see how
4423 your fancy Web page will look for a residential user who
4424 is connected only through a slow link.
4425 You should not use only one pipe for both directions, unless
4426 you want to simulate a half-duplex medium (e.g.\& AppleTalk,
4428 It is not necessary that both pipes have the same configuration,
4429 so we can also simulate asymmetric links.
4431 Should we want to verify network performance with the RED queue
4432 management algorithm:
4434 .Dl "ipfw add pipe 1 ip from any to any"
4435 .Dl "dnctl pipe 1 config bw 500Kbit/s queue 100 red 0.002/30/80/0.1"
4437 Another typical application of the traffic shaper is to
4438 introduce some delay in the communication.
4439 This can significantly affect applications which do a lot of Remote
4440 Procedure Calls, and where the round-trip-time of the
4441 connection often becomes a limiting factor much more than
4444 .Dl "ipfw add pipe 1 ip from any to any out"
4445 .Dl "ipfw add pipe 2 ip from any to any in"
4446 .Dl "dnctl pipe 1 config delay 250ms bw 1Mbit/s"
4447 .Dl "dnctl pipe 2 config delay 250ms bw 1Mbit/s"
4449 Per-flow queueing can be useful for a variety of purposes.
4450 A very simple one is counting traffic:
4452 .Dl "ipfw add pipe 1 tcp from any to any"
4453 .Dl "ipfw add pipe 1 udp from any to any"
4454 .Dl "ipfw add pipe 1 ip from any to any"
4455 .Dl "dnctl pipe 1 config mask all"
4457 The above set of rules will create queues (and collect
4458 statistics) for all traffic.
4459 Because the pipes have no limitations, the only effect is
4460 collecting statistics.
4461 Note that we need 3 rules, not just the last one, because
4464 tries to match IP packets it will not consider ports, so we
4465 would not see connections on separate ports as different
4468 A more sophisticated example is limiting the outbound traffic
4469 on a net with per-host limits, rather than per-network limits:
4471 .Dl "ipfw add pipe 1 ip from 192.168.2.0/24 to any out"
4472 .Dl "ipfw add pipe 2 ip from any to 192.168.2.0/24 in"
4473 .Dl "dnctl pipe 1 config mask src-ip 0x000000ff bw 200Kbit/s queue 20Kbytes"
4474 .Dl "dnctl pipe 2 config mask dst-ip 0x000000ff bw 200Kbit/s queue 20Kbytes"
4476 In the following example, we need to create several traffic bandwidth
4477 classes and we need different hosts/networks to fall into different classes.
4478 We create one pipe for each class and configure them accordingly.
4479 Then we create a single table and fill it with IP subnets and addresses.
4480 For each subnet/host we set the argument equal to the number of the pipe
4482 Then we classify traffic using a single rule:
4484 .Dl "dnctl pipe 1 config bw 1000Kbyte/s"
4485 .Dl "dnctl pipe 4 config bw 4000Kbyte/s"
4487 .Dl "ipfw table T1 create type addr"
4488 .Dl "ipfw table T1 add 192.168.2.0/24 1"
4489 .Dl "ipfw table T1 add 192.168.0.0/27 4"
4490 .Dl "ipfw table T1 add 192.168.0.2 1"
4492 .Dl "ipfw add pipe tablearg ip from 'table(T1)' to any"
4496 action, the table entries may include hostnames and IP addresses.
4498 .Dl "ipfw table T2 create type addr valtype ipv4"
4499 .Dl "ipfw table T2 add 192.168.2.0/24 10.23.2.1"
4500 .Dl "ipfw table T2 add 192.168.0.0/27 router1.dmz"
4502 .Dl "ipfw add 100 fwd tablearg ip from any to 'table(T2)'"
4504 In the following example per-interface firewall is created:
4506 .Dl "ipfw table IN create type iface valtype skipto,fib"
4507 .Dl "ipfw table IN add vlan20 12000,12"
4508 .Dl "ipfw table IN add vlan30 13000,13"
4509 .Dl "ipfw table OUT create type iface valtype skipto"
4510 .Dl "ipfw table OUT add vlan20 22000"
4511 .Dl "ipfw table OUT add vlan30 23000"
4513 .Dl "ipfw add 100 setfib tablearg ip from any to any recv 'table(IN)' in"
4514 .Dl "ipfw add 200 skipto tablearg ip from any to any recv 'table(IN)' in"
4515 .Dl "ipfw add 300 skipto tablearg ip from any to any xmit 'table(OUT)' out"
4517 The following example illustrate usage of flow tables:
4519 .Dl "ipfw table fl create type flow:src-ip,proto,dst-ip,dst-port"
4520 .Dl "ipfw table fl add 2a02:6b8:77::88,tcp,2a02:6b8:77::99,80 11"
4521 .Dl "ipfw table fl add 10.0.0.1,udp,10.0.0.2,53 12"
4523 .Dl "ipfw add 100 allow ip from any to any flow 'table(fl,11)' recv ix0"
4525 To add a set of rules atomically, e.g.\& set 18:
4527 .Dl "ipfw set disable 18"
4528 .Dl "ipfw add NN set 18 ... # repeat as needed"
4529 .Dl "ipfw set enable 18"
4531 To delete a set of rules atomically the command is simply:
4533 .Dl "ipfw delete set 18"
4535 To test a ruleset and disable it and regain control if something goes wrong:
4537 .Dl "ipfw set disable 18"
4538 .Dl "ipfw add NN set 18 ... # repeat as needed"
4539 .Dl "ipfw set enable 18; echo done; sleep 30 && ipfw set disable 18"
4541 Here if everything goes well, you press control-C before the "sleep"
4542 terminates, and your ruleset will be left active.
4543 Otherwise, e.g.\& if
4544 you cannot access your box, the ruleset will be disabled after
4545 the sleep terminates thus restoring the previous situation.
4547 To show rules of the specific set:
4549 .Dl "ipfw set 18 show"
4551 To show rules of the disabled set:
4553 .Dl "ipfw -S set 18 show"
4555 To clear a specific rule counters of the specific set:
4557 .Dl "ipfw set 18 zero NN"
4559 To delete a specific rule of the specific set:
4561 .Dl "ipfw set 18 delete NN"
4562 .Ss NAT, REDIRECT AND LSNAT
4563 First redirect all the traffic to nat instance 123:
4565 .Dl "ipfw add nat 123 all from any to any"
4567 Then to configure nat instance 123 to alias all the outgoing traffic with ip
4568 192.168.0.123, blocking all incoming connections, trying to keep
4569 same ports on both sides, clearing aliasing table on address change
4570 and keeping a log of traffic/link statistics:
4572 .Dl "ipfw nat 123 config ip 192.168.0.123 log deny_in reset same_ports"
4574 Or to change address of instance 123, aliasing table will be cleared (see
4577 .Dl "ipfw nat 123 config ip 10.0.0.1"
4579 To see configuration of nat instance 123:
4581 .Dl "ipfw nat 123 show config"
4583 To show logs of all instances:
4585 .Dl "ipfw nat show log"
4587 To see configurations of all instances:
4589 .Dl "ipfw nat show config"
4591 Or a redirect rule with mixed modes could looks like:
4592 .Bd -literal -offset 2n
4593 ipfw nat 123 config redirect_addr 10.0.0.1 10.0.0.66
4594 redirect_port tcp 192.168.0.1:80 500
4595 redirect_proto udp 192.168.1.43 192.168.1.1
4596 redirect_addr 192.168.0.10,192.168.0.11
4598 redirect_port tcp 192.168.0.1:80,192.168.0.10:22
4602 or it could be split in:
4603 .Bd -literal -offset 2n
4604 ipfw nat 1 config redirect_addr 10.0.0.1 10.0.0.66
4605 ipfw nat 2 config redirect_port tcp 192.168.0.1:80 500
4606 ipfw nat 3 config redirect_proto udp 192.168.1.43 192.168.1.1
4607 ipfw nat 4 config redirect_addr 192.168.0.10,192.168.0.11,192.168.0.12
4609 ipfw nat 5 config redirect_port tcp
4610 192.168.0.1:80,192.168.0.10:22,192.168.0.20:25 500
4613 Sometimes you may want to mix NAT and dynamic rules.
4614 It could be achieved with
4619 Problem is, you need to create dynamic rule before NAT and check it
4620 after NAT actions (or vice versa) to have consistent addresses and ports.
4623 option will trigger activation of existing dynamic state, and action of such
4624 rule will be performed as soon as rule is matched.
4627 rule packet need to be passed to NAT, not allowed as soon is possible.
4629 There is example of set of rules to achieve this.
4630 Bear in mind that this is example only and it is not very useful by itself.
4632 On way out, after all checks place this rules:
4634 .Dl "ipfw add allow record-state defer-action"
4635 .Dl "ipfw add nat 1"
4637 And on way in there should be something like this:
4639 .Dl "ipfw add nat 1"
4640 .Dl "ipfw add check-state"
4642 Please note, that first rule on way out doesn't allow packet and doesn't
4643 execute existing dynamic rules.
4644 All it does, create new dynamic rule with
4646 action, if it is not created yet.
4647 Later, this dynamic rule is used on way in by
4650 .Ss CONFIGURING CODEL, PIE, FQ-CODEL and FQ-PIE AQM
4654 AQM can be configured for
4664 AQM using default configuration for traffic from 192.168.0.0/24 and 1Mbits/s
4667 .Dl "dnctl pipe 1 config bw 1mbits/s codel"
4668 .Dl "ipfw add 100 pipe 1 ip from 192.168.0.0/24 to any"
4674 AQM using different configurations parameters for traffic from
4675 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4677 .Dl "dnctl pipe 1 config bw 1mbits/s"
4678 .Dl "dnctl queue 1 config pipe 1 codel target 8ms interval 160ms ecn"
4679 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4685 AQM using default configuration for traffic from 192.168.0.0/24 and 1Mbits/s
4688 .Dl "dnctl pipe 1 config bw 1mbits/s pie"
4689 .Dl "ipfw add 100 pipe 1 ip from 192.168.0.0/24 to any"
4695 AQM using different configuration parameters for traffic from
4696 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4698 .Dl "dnctl pipe 1 config bw 1mbits/s"
4699 .Dl "dnctl queue 1 config pipe 1 pie target 20ms tupdate 30ms ecn"
4700 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4705 AQM can be configured for
4711 scheduler using different configurations parameters for traffic from
4712 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4714 .Dl "dnctl pipe 1 config bw 1mbits/s"
4715 .Dl "dnctl sched 1 config pipe 1 type fq_codel"
4716 .Dl "dnctl queue 1 config sched 1"
4717 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4721 default configuration for a
4723 such as disable ECN and change the
4727 .Dl "dnctl sched 1 config pipe 1 type fq_codel target 10ms noecn"
4733 scheduler using different configurations parameters for traffic from
4734 192.168.0.0/24 and 1Mbits/s rate limit, we do:
4736 .Dl "dnctl pipe 1 config bw 1mbits/s"
4737 .Dl "dnctl sched 1 config pipe 1 type fq_pie"
4738 .Dl "dnctl queue 1 config sched 1"
4739 .Dl "ipfw add 100 queue 1 ip from 192.168.0.0/24 to any"
4741 The configurations of
4744 can be changed in a similar way as for
4768 utility first appeared in
4773 Stateful extensions were introduced in
4776 was introduced in Summer 2002.
4778 .An Ugen J. S. Antsilevich ,
4779 .An Poul-Henning Kamp ,
4783 .An Rasool Al-Saadi .
4786 API based upon code written by
4790 Dummynet has been introduced by Luigi Rizzo in 1997-1998.
4792 Some early work (1999-2000) on the
4794 traffic shaper supported by Akamba Corp.
4796 The ipfw core (ipfw2) has been completely redesigned and
4797 reimplemented by Luigi Rizzo in summer 2002.
4800 options have been added by various developers over the years.
4803 In-kernel NAT support written by
4804 .An Paolo Pisati Aq Mt piso@FreeBSD.org
4805 as part of a Summer of Code 2005 project.
4809 support has been developed by
4810 .An The Centre for Advanced Internet Architectures (CAIA) Aq http://www.caia.swin.edu.au .
4811 The primary developers and maintainers are David Hayes and Jason But.
4812 For further information visit:
4813 .Aq http://www.caia.swin.edu.au/urp/SONATA
4815 Delay profiles have been developed by Alessandro Cerri and
4816 Luigi Rizzo, supported by the
4817 European Commission within Projects Onelab and Onelab2.
4819 CoDel, PIE, FQ-CoDel and FQ-PIE AQM for Dummynet have been implemented by
4820 .An The Centre for Advanced Internet Architectures (CAIA)
4821 in 2016, supported by The Comcast Innovation Fund.
4822 The primary developer is
4825 The syntax has grown over the years and sometimes it might be confusing.
4826 Unfortunately, backward compatibility prevents cleaning up mistakes
4827 made in the definition of the syntax.
4831 Misconfiguring the firewall can put your computer in an unusable state,
4832 possibly shutting down network services and requiring console access to
4833 regain control of it.
4835 Incoming packet fragments diverted by
4837 are reassembled before delivery to the socket.
4838 The action used on those packet is the one from the
4839 rule which matches the first fragment of the packet.
4841 Packets diverted to userland, and then reinserted by a userland process
4842 may lose various packet attributes.
4843 The packet source interface name
4844 will be preserved if it is shorter than 8 bytes and the userland process
4845 saves and reuses the sockaddr_in
4848 otherwise, it may be lost.
4849 If a packet is reinserted in this manner, later rules may be incorrectly
4850 applied, making the order of
4852 rules in the rule sequence very important.
4854 Dummynet drops all packets with IPv6 link-local addresses.
4860 may not behave as expected.
4861 In particular, incoming SYN packets may
4862 have no uid or gid associated with them since they do not yet belong
4863 to a TCP connection, and the uid/gid associated with a packet may not
4864 be as expected if the associated process calls
4866 or similar system calls.
4868 Rule syntax is subject to the command line environment and some patterns
4869 may need to be escaped with the backslash character
4870 or quoted appropriately.
4872 Due to the architecture of
4874 ipfw nat is not compatible with the TCP segmentation offloading (TSO).
4875 Thus, to reliably nat your network traffic, please disable TSO
4879 ICMP error messages are not implicitly matched by dynamic rules
4880 for the respective conversations.
4881 To avoid failures of network error detection and path MTU discovery,
4882 ICMP error messages may need to be allowed explicitly through static
4889 actions may lead to confusing behaviour if ruleset has mistakes,
4890 and/or interaction with other subsystems (netgraph, dummynet, etc.) is used.
4891 One possible case for this is packet leaving
4893 in subroutine on the input pass, while later on output encountering unpaired
4896 As the call stack is kept intact after input pass, packet will suddenly
4897 return to the rule number used on input pass, not on output one.
4898 Order of processing should be checked carefully to avoid such mistakes.
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